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/tsc.h b/arch/x86/include/asm/tsc.h
index ad0f5c4..38ae163 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -1,8 +1,8 @@
 /*
  * x86 TSC related functions
  */
-#ifndef ASM_X86__TSC_H
-#define ASM_X86__TSC_H
+#ifndef _ASM_X86_TSC_H
+#define _ASM_X86_TSC_H
 
 #include <asm/processor.h>
 
@@ -59,4 +59,4 @@
 
 extern int notsc_setup(char *);
 
-#endif /* ASM_X86__TSC_H */
+#endif /* _ASM_X86_TSC_H */