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/termbits.h

@@ -1,5 +1,5 @@
-#ifndef ASM_X86__TERMBITS_H
-#define ASM_X86__TERMBITS_H
+#ifndef _ASM_X86_TERMBITS_H
+#define _ASM_X86_TERMBITS_H
 
 #include <linux/posix_types.h>
 
@@ -195,4 +195,4 @@ struct ktermios {
 #define	TCSADRAIN	1
 #define	TCSAFLUSH	2
 
-#endif /* ASM_X86__TERMBITS_H */
+#endif /* _ASM_X86_TERMBITS_H */