x86/cmpxchg, locking/atomics: Remove superfluous definitions

x86/cmpxchg, locking/atomics: Remove superfluous definitions

cmpxchg contained definitions for unused (x)add_* operations, dating back
to the original ticket spinlock implementation. Nowadays these are
unused so remove them.

Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hpa@zytor.com
Link: http://lkml.kernel.org/r/1474913478-17757-1-git-send-email-n.borisov.lkml@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>