Fix us waits in embassy hanging

[bugadani]

The check removed in #737 seems to break waits in the order of a few microseconds. In these cases, the interrupt handler does not fire even though the TRM seems to indicate it should. This PR restores the check and makes a few additional simplifications.

TIMG0 driver seems unaffected.

Must

• The code compiles without errors or warnings.
• All examples work.
• cargo fmt was run.
• Your changes were added to the CHANGELOG.md in the proper section.
• You updated existing examples or added examples (if applicable).
• Added examples are checked in CI

Nice to have

• You add a description of your work to this PR.
• You added proper docs for your newly added features and code.

[MabezDev]

LGTM, thanks for the fix!