base: genlock: Remove genlock_release_lock and associated ioctl

Allowing a lock to be asynchronously released while a handle
was still active turned out to be too dangerous to use in a
multi-threaded environment and it served no pratical
purpose anyway.  Handles now hold an attached lock until they
are destroyed.

CRs-fixed: 333141
Change-Id: Ic0dedbad8050ff01927ddb165c65a939bf297c10
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>