Revert flash_get_value for M2351 done in PR#8589

[deepikabhavnani]

Description

flash_get_erase_value is added in hal/TARGET_FLASH_CMSIS_ALGO/flash_common_algo.c
duplicate copy of same function in targets/TARGET_NUVOTON/TARGET_M2351/flash_api.c
resulted in build issues with secure build

See https://github.com/ARMmbed/mbed-os/pull/8589/files#r232354584 for more details.

Pull request type

[X] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Docs update
[ ] Test update
[ ] Breaking change

CC @ARMmbed/team-nuvoton

[davidsaada]

@deepikabhavnani Reason I added it there was the fact that it wouldn't recognize the changes added in hal/TARGET_FLASH_CMSIS_ALGO/flash_common_algo.c. Did you try building the flashiap test (under mbed_drivers)?

[deepikabhavnani]

@davidsaada - I will try to build the test once, secure side image is in working condition. In #8589 I guess M2351 is the outlier, it uses all the definitions from common layer "hal/TARGET_FLASH_CMSIS_ALGO/flash_common_algo.c". You can see the difference between any other target "flash_api.c" and M2351 - flash_api.c

[deepikabhavnani]

Added secure side library and CMSE file for the changes in secure side https://github.com/ARMmbed/mbed-os/pull/8589/files#diff-a91b86027e0469c7339b13de32617b03R263

[deepikabhavnani]

+-------------------------+-------------------+-------------------------------------+--------+--------------------+-------------+
| target                  | platform_name     | test suite                          | result | elapsed_time (sec) | copy_method |
+-------------------------+-------------------+-------------------------------------+--------+--------------------+-------------+
| NUMAKER_PFM_M2351-ARMC6 | NUMAKER_PFM_M2351 | mbed-os-tests-mbed_drivers-flashiap | OK     | 17.5               | default     |
+-------------------------+-------------------+-------------------------------------+--------+--------------------+-------------+
mbedgt: test suite results: 1 OK
mbedgt: test case report:
+-------------------------+-------------------+-------------------------------------+-----------------------------------+--------+--------+--------+--------------------+
| target                  | platform_name     | test suite                          | test case                         | passed | failed | result | elapsed_time (sec) |
+-------------------------+-------------------+-------------------------------------+-----------------------------------+--------+--------+--------+--------------------+
| NUMAKER_PFM_M2351-ARMC6 | NUMAKER_PFM_M2351 | mbed-os-tests-mbed_drivers-flashiap | FlashIAP - init                   | 1      | 0      | OK     | 0.05               |
| NUMAKER_PFM_M2351-ARMC6 | NUMAKER_PFM_M2351 | mbed-os-tests-mbed_drivers-flashiap | FlashIAP - program                | 1      | 0      | OK     | 0.32               |
| NUMAKER_PFM_M2351-ARMC6 | NUMAKER_PFM_M2351 | mbed-os-tests-mbed_drivers-flashiap | FlashIAP - program across sectors | 1      | 0      | OK     | 0.21               |
| NUMAKER_PFM_M2351-ARMC6 | NUMAKER_PFM_M2351 | mbed-os-tests-mbed_drivers-flashiap | FlashIAP - program errors         | 1      | 0      | OK     | 0.05               |
| NUMAKER_PFM_M2351-ARMC6 | NUMAKER_PFM_M2351 | mbed-os-tests-mbed_drivers-flashiap | FlashIAP - timing                 | 1      | 0      | OK     | 1.03               |
+-------------------------+-------------------+-------------------------------------+-----------------------------------+--------+--------+--------+--------------------+
mbedgt: test case results: 5 OK
mbedgt: completed in 23.12 sec

[0xc0170]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 3608
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/8699/

Triggering tests

/morph test
/morph export-build
/morph mbed2-build

[mbed-ci]

Test : FAILURE

Build number : 3384
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/8699/3384

[mbed-ci]

Exporter Build : SUCCESS

Build number : 3212
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/8699/

[cmonr]

Note: This PR is now a part of a rollup PR (#8733).

In order to expidite remaining CI testing, this PR has been bundled into the above rollup PR.

No further work is needed here, as once that PR is merged, this PR will also be closed and marked as merged.

If any more commits are made in this PR, this PR will remain open and have to go through CI on its own.