BLE: remove limitation in the Cordio to update adv payload

[pan-]

Summary of changes

Nothing in the Bluetooth standard prevents update of advertising payload while advertising is active.
This limitation wasn't present in previous version of the stack and is not present for extended advertising. It is removed from legacy advertising with this patch.

Documentation

None

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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)
[] Covered by existing mbed-os tests (Greentea or Unittest)
[x] Tests / results supplied as part of this PR

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Reviewers

@paul-szczepanek-arm

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[ciarmcom]

@pan-, thank you for your changes.
@paul-szczepanek-arm @ARMmbed/mbed-os-pan @ARMmbed/mbed-os-maintainers please review.

[0xc0170]

CI started

[mbed-ci]

Test run: SUCCESS

Summary: 6 of 6 test jobs passed
Build number : 1
Build artifacts

[0xc0170]

All green but the incorrect status reported from mergify makes it red. I'll merge as it can't be overwritten.