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/geode.h b/arch/x86/include/asm/geode.h
index 3f3444b..ad3c2ed 100644
--- a/arch/x86/include/asm/geode.h
+++ b/arch/x86/include/asm/geode.h
@@ -7,8 +7,8 @@
  * as published by the Free Software Foundation.
  */
 
-#ifndef ASM_X86__GEODE_H
-#define ASM_X86__GEODE_H
+#ifndef _ASM_X86_GEODE_H
+#define _ASM_X86_GEODE_H
 
 #include <asm/processor.h>
 #include <linux/io.h>
@@ -250,4 +250,4 @@
 static inline int mfgpt_timer_setup(void) { return 0; }
 #endif
 
-#endif /* ASM_X86__GEODE_H */
+#endif /* _ASM_X86_GEODE_H */