Revert "mailbox: forward the hrtimer if not queued and under a lock"

This reverts commit bb2220e0 which is
commit bca1a100 upstream.

It breaks the Android kernel ABI and is not needed for Android devices,
so it is safe to revert for now.  If it is determined that it is needed
in the future, it can be brought back in an abi-preserving way.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I5e9282790af470cf09d353c7e1e54e9f93f01d85