x86: consolidate header guards

This patch is the result of an automatic script that consolidates the
format of all the headers in include/asm-x86/.

The format:

1. No leading underscore. Names with leading underscores are reserved.
2. Pathname components are separated by two underscores. So we can
   distinguish between mm_types.h and mm/types.h.
3. Everything except letters and numbers are turned into single
   underscores.

Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
diff --git a/include/asm-x86/ist.h b/include/asm-x86/ist.h
index 6ec6cee..35a2fe9 100644
--- a/include/asm-x86/ist.h
+++ b/include/asm-x86/ist.h
@@ -1,5 +1,5 @@
-#ifndef _ASM_IST_H
-#define _ASM_IST_H
+#ifndef ASM_X86__IST_H
+#define ASM_X86__IST_H
 
 /*
  * Include file for the interface to IST BIOS
@@ -31,4 +31,4 @@
 extern struct ist_info ist_info;
 
 #endif	/* __KERNEL__ */
-#endif	/* _ASM_IST_H */
+#endif /* ASM_X86__IST_H */