NRF52840: Use 2 region memory model for the ARM toolchain

[hugueskamba]

Summary of changes

Use two memory region model to be able to compile with Microlib. This change should cause any regression when building with the standard C library and all existing tests should pass for all targets that use the scatter file modified in this PR.

Suppport for uARM toolchain has not been added as it is being deprecated. Building with Microlib will be possible after this PR is merged.

After the two PRs are merged, one could test the targets that use the scatter file modified in this PR to ensure they run fine with Microlib by following the steps here to enable small library support for each target of interest.

Impact of changes

Migration actions required

Documentation

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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

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[ciarmcom]

@hugueskamba, thank you for your changes.
@ARMmbed/mbed-os-maintainers please review.

[bulislaw]

LGTM

[bulislaw]

@linlingao @desmond-blue @pan- I'm assuming that won't have any impact on Cordio? And I don't think we support softdevices on this board?

[adbridge]

I'll start ci on this pending an answer to @bulislaw 's question

[mbed-ci]

Test run: FAILED

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

Failed test jobs:

• jenkins-ci/mbed-os-ci_cloud-client-pytest

[desmond-blue]

@bulislaw No impact on Cordio, however I think this board is still supporting SoftDevice if configuring mbed_app.json correctly, it's just not a default option. Any other comments?

[adbridge]

Looks like a CI issue so re-running

[mbed-ci]

Test run: FAILED

Summary: 1 of 4 test jobs failed
Build number : 2
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_build-IAR

[hugueskamba]

Test run: FAILED

Summary: 1 of 4 test jobs failed
Build number : 2
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_build-IAR

@adbridge The failure seems to have been caused by a lack of license for the IAR compiler. Can you please fix and re-run? Thanks.

[0xc0170]

CI started

[mbed-ci]

Test run: SUCCESS

Summary: 11 of 11 test jobs passed
Build number : 3
Build artifacts