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>

arch/x86/include/asm/bug.h

@@ -1,5 +1,5 @@
-#ifndef ASM_X86__BUG_H
-#define ASM_X86__BUG_H
+#ifndef _ASM_X86_BUG_H
+#define _ASM_X86_BUG_H
 
 #ifdef CONFIG_BUG
 #define HAVE_ARCH_BUG
@@ -36,4 +36,4 @@ do {								\
 #endif /* !CONFIG_BUG */
 
 #include <asm-generic/bug.h>
-#endif /* ASM_X86__BUG_H */
+#endif /* _ASM_X86_BUG_H */