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

This reverts commit 16b5013f which is
commit bca1a1004615efe141fd78f360ecc48c60bc4ad5 upstream.

It breaks the kernel api and isn't anything that is relevant for Android
systems as it was already fixed in Android in a different way, so it can
be reverted.

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I49bf9cf61438dbd002eaf89dc0c1ce514fd66e17