submodule: bump openthread from `adea4c4` to `c2dd7eb` (#268)
submodule: bump openthread from `adea4c4` to `c2dd7eb` (#268)

Bumps [openthread](https://github.com/openthread/openthread) from `adea4c4` to `c2dd7eb`.
- [Commits](https://github.com/openthread/openthread/compare/adea4c4b2af20ae5180232988843f0b94b43b230...c2dd7eb66d5d806adf6fb2dcb35e2070e97f2e78)

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

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

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
openthread/ot-cc2538,openthread/ot-cc2538