submodule: bump openthread from `531cb34` to `f7802d6` (#20)
submodule: bump openthread from `531cb34` to `f7802d6` (#20)

Bumps [openthread](https://github.com/openthread/openthread) from `531cb34` to `f7802d6`.
- [Commits](https://github.com/openthread/openthread/compare/531cb3484915719e347dd84a82c1b9872e0c483c...f7802d60a17a355bbfd02f25a34035bddf5ee333)

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

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