Revert "futex: Ensure lock/unlock symetry versus pi_lock and hash bucket lock"

[ Upstream commit 6a773b70cf105b46298ed3b44e77c102ce31d9ec ]

Drop the RT fixup, the futex code will be changed to avoid the need for
the workaround.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>