Musca-B1: Grant Non-Secure access for MHU0 on EXP0

[GaborAbonyi]

Summary of changes

For Musca-B1 target, MHU0 can be accessed from Non-Secure code, but this configuration can only be made in the secure side. This change grants Non-Secure access for MHU0 on EXP0.

Impact of changes

Migration actions required

Documentation

N/A

---

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)

---

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

---

[ciarmcom]

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

[0xc0170]

CI restarted

[mbed-ci]

Test run: SUCCESS

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