submodule: bump openthread from `12a1e61` to `f6df50c` (#414)
submodule: bump openthread from `12a1e61` to `f6df50c` (#414)

Bumps [openthread](https://github.com/openthread/openthread) from `12a1e61` to `f6df50c`.
- [Commits](https://github.com/openthread/openthread/compare/12a1e618b26075a27ab07c8552e5320007058d60...f6df50cde654d55bc55ce511daf2a077f2bc68a3)

---
updated-dependencies:
- dependency-name: openthread
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
openthread/ot-efr32,openthread/ot-efr32,openthread/ot-efr32