x86: Fix ASM_X86__ header guards

Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/include/asm/rwlock.h b/arch/x86/include/asm/rwlock.h
index 48a3109..6a8c0d6 100644
--- a/arch/x86/include/asm/rwlock.h
+++ b/arch/x86/include/asm/rwlock.h
@@ -1,8 +1,8 @@
-#ifndef ASM_X86__RWLOCK_H
-#define ASM_X86__RWLOCK_H
+#ifndef _ASM_X86_RWLOCK_H
+#define _ASM_X86_RWLOCK_H
 
 #define RW_LOCK_BIAS		 0x01000000
 
 /* Actual code is in asm/spinlock.h or in arch/x86/lib/rwlock.S */
 
-#endif /* ASM_X86__RWLOCK_H */
+#endif /* _ASM_X86_RWLOCK_H */