set the tolerance to 5% if NO_SYSTICK is enabled

[ithinuel]

Description

Fixes the issue raised on CI on the NRF 51 device.
The value of 5% is chosen to match the tolerance applied to lp_tickers that are also often RTC-backed.

Related PR

• Stats - Update ticker read mechanism #7063

Pull request type

[X] Fix
[ ] Refactor
[ ] New target
[ ] Feature
[ ] Breaking change

[adbridge]

@ithinuel Looks like a possible real error on pr-head:

Build failures:

  * K64F::ARM::TESTS-MBED_DRIVERS-TIMER

        Building project timer (K64F, ARM)

        Scan: ARM

        Scan: timer

        Scan: FEATURE_LWIP

        Scan: FEATURE_STORAGE

        Compile [100.0%]: main.cpp

        [Error] main.cpp@415,0:  #19: extra text after expected end of number

        [Error] main.cpp@437,0:  #19: extra text after expected end of number

        [Error] main.cpp@458,0:  #19: extra text after expected end of number

        [Error] main.cpp@480,0:  #19: extra text after expected end of number

        [Error] main.cpp@509,0:  #19: extra text after expected end of number

        [Error] main.cpp@527,0:  #19: extra text after expected end of number

        [Error] main.cpp@611,0:  #19: extra text after expected end of number

        [Error] main.cpp@648,0:  #19: extra text after expected end of number

        [Error] main.cpp@675,0:  #19: extra text after expected end of number

        [Error] main.cpp@730,0:  #19: extra text after expected end of number

[cmonr]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 2214
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/7070/

Triggering tests

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

[mbed-ci]

Test : SUCCESS

Build number : 2007
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/7070/2007

[mbed-ci]

Exporter Build : SUCCESS

Build number : 1841
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/7070/

[cmonr]

/morph uvisor-test

[cmonr]

/morph uvisor-test

[cmonr]

/morph uvisor-test

[maciejbocianski]

This bug(test failures) likely arose when NRF51 us_ticker implementation was changed from rtc to timer based (9ef0083). Before both lp_ticker and us_ticker were rtc based

[0xc0170]

/morph uvisor-test