DISCO_L4R9I correct LED pins

[jeromecoutant]

Summary of changes

On DISCO-L4R9I board LD1 is not mapped on MCU pins.

See Board User Manual:
"LD1 (orange) is managed by MFX function"
MFX functions are currently not supported in MBED.

@MarceloSalazar
@LMESTM

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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[0xc0170]

CI started

[mbed-ci]

Test run: FAILED

Summary: 1 of 7 test jobs failed
Build number : 1
Build artifacts

Failed test jobs:

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

[0xc0170]

Client restarted