x86, locking: Use no more OOSTORE nonsense

Paul reported that X86_OOSTORE is dead, yay! Update a comment and
remove a newly added reference.

Reported-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20140611090509.GC3588@twins.programming.kicks-ass.net


Signed-off-by: Ingo Molnar <mingo@kernel.org>