locking/x86: Remove the unused atomic_inc_short() methd

It is completely unused and implemented only on x86.
Remove it.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170526172900.91058-1-dvyukov@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/tile/lib/atomic_asm_32.S

@@ -24,8 +24,7 @@
  * has an opportunity to return -EFAULT to the user if needed.
  * The 64-bit routines just return a "long long" with the value,
  * since they are only used from kernel space and don't expect to fault.
- * Support for 16-bit ops is included in the framework but we don't provide
- * any (x86_64 has an atomic_inc_short(), so we might want to some day).
+ * Support for 16-bit ops is included in the framework but we don't provide any.
  *
  * Note that the caller is advised to issue a suitable L1 or L2
  * prefetch on the address being manipulated to avoid extra stalls.

arch/x86/include/asm/atomic.h

@@ -246,19 +246,6 @@ static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
 	return c;
 }
 
-/**
- * atomic_inc_short - increment of a short integer
- * @v: pointer to type int
- *
- * Atomically adds 1 to @v
- * Returns the new value of @u
- */
-static __always_inline short int atomic_inc_short(short int *v)
-{
-	asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
-	return *v;
-}
-
 #ifdef CONFIG_X86_32
 # include <asm/atomic64_32.h>
 #else