EFM32: Enable RESET_REASON and WATCHDOG for EFM32GG11_STK3701

[amq]

Description (required)

All EFM32 targets list RESET_REASON and WATCHDOG in device_has, apart of EFM32GG11_STK3701. There seems to be no reason for this, it was probably just missed by mistake. I have validated both features on a physical device and confirmed that they work.

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Pull request type (required)

[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 (required)

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

Migration actions required (required)

None.

[ciarmcom]

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

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CI started

[mbed-ci]

Test run: FAILED

Summary: 1 of 4 test jobs failed
Build number : 1
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Failed test jobs:

• jenkins-ci/mbed-os-ci_unittests

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[mbed-ci]

Test run: FAILED

Summary: 1 of 11 test jobs failed
Build number : 2
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Failed test jobs:

• jenkins-ci/mbed-os-ci_greentea-test

[0xc0170]

Test failed because of #11862, we will investigate

[adbridge]

CI restarted

[mbed-ci]

Test run: SUCCESS

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