Test with MAX32670, add upload method and fix ticker bug

[multiplemonomials]

Summary of changes

I picked up a MAX32670 board and tested Mbed CE on it, and this MR fixes a few issues I discovered.

Impact of changes

• Upload method support added for MAX32670EVKIT
• MAX32670 linker script updated to support memory banks
• Bug fixed where MAX32760 us and lp tickers would never fire their interrupt again once disabled

Migration actions required

Documentation

None

---

Pull request type

[] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[X] 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

100% Greentea tests pass on this target!

---