x86, cmpxchg: <linux/alternative.h> has LOCK_PREFIX

Not <linux/bitops.h>.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Link: http://lkml.kernel.org/r/4E5BCC40.3030501@goop.orgSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/cmpxchg_32.h

 #ifndef _ASM_X86_CMPXCHG_32_H
 #define _ASM_X86_CMPXCHG_32_H
 
-#include <linux/bitops.h> /* for LOCK_PREFIX */
+#include <asm/alternative.h> /* Provides LOCK_PREFIX */
 
 /*
  * Note: if you use set64_bit(), __cmpxchg64(), or their variants, you