Moved CP Max recv len into mbed_lib.json

[AnttiKauppila]

Summary of changes

Moved CP Max recv len into mbed_lib.json so it can be configured by end developer when needed.
According to [3GPP-TS_24.008] the maximum size for Non-IP link MTU is 1358 octets to prevent fragmentation in the backbone network. Therefore reduced the maximum size to follow the standard.

Impact of changes

Migration actions required

Documentation

mbed_lib.json has a specific help for the value

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Pull request type

[X] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

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Test results

[] No Tests required for this change (E.g docs only update)
[X] Covered by existing mbed-os tests (Greentea or Unittest)
[] Tests / results supplied as part of this PR

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Reviewers

@ARMmbed/mbed-os-wan

[kjbracey]

Can you justify the value reduction? Non-functional change for existing modems/networks?

[AnttiKauppila]

@kjbracey-arm Updated summary to have reasoning for value reduction

[kjbracey]

@kjbracey-arm Updated summary to have reasoning for value reduction

Ta. Take care to also update Git commit messages, not just the GitHub description, as it's the Git commit message that's permanent.

[AnttiKauppila]

Commit msg updated

[kjbracey]

CI started

[mbed-ci]

Test run: SUCCESS

Summary: 11 of 11 test jobs passed
Build number : 1
Build artifacts