ARM: remove __bad_xchg definition

We want link errors if xchg() is called for a variable size we do not
support.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/cmpxchg.h

@@ -94,6 +94,7 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size
 		break;
 #endif
 	default:
+		/* Cause a link-time error, the xchg() size is not supported */
 		__bad_xchg(ptr, size), ret = 0;
 		break;
 	}

arch/arm/kernel/traps.c

@@ -749,14 +749,6 @@ late_initcall(arm_mrc_hook_init);
 
 #endif
 
-void __bad_xchg(volatile void *ptr, int size)
-{
-	pr_err("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
-	       __builtin_return_address(0), ptr, size);
-	BUG();
-}
-EXPORT_SYMBOL(__bad_xchg);
-
 /*
  * A data abort trap was taken, but we did not handle the instruction.
  * Try to abort the user program, or panic if it was the kernel.