OWNERS: prune inactive members

Enforce the policy[1] which requires that subproject maintainers are
only list developers who have been active in the project.

Removed developers that have not been active per that policy from
OWNERS.

[1]: https://github.com/openbmc/docs/commit/1b531cd0d861d9c1d9ff81fb782e43f15c3c48d9

Change-Id: I752a375a9f080ce4809387405c7ac8b245825145
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>