NUCLEO_WB55RG - add device name "STM32WB55RGVx"

[JanneKiiskila]

Summary of changes

Add device name for NUCLEO_WB55RG target.

Bootloader compilation will require the device to be in place,
it uses that to pick up the CMSIS-pack info from the index.json.

[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)

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

Reviewers

@ARMmbed/team-st-mcd @0xc0170

[0xc0170]

CI started

[0xc0170]

CI is having an internal issue, will restart once fixed.

[mbed-ci]

Test run: SUCCESS

Summary: 11 of 11 test jobs passed
Build number : 2
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[0xc0170]

@JanneKiiskila target json was updated in one of earlier PRs, can you rebase to resolve the conflict, will restart CI asap.

[JanneKiiskila]

@0xc0170 , done, I also turned the bootloader to be true. I think that needs to be changed, too. That's whole reason the changes were started, actually.

[0xc0170]

CI restarted

[mbed-ci]

Test run: SUCCESS

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