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/setup.h b/arch/x86/include/asm/setup.h
index 11b6cc1..f12d372 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -1,5 +1,5 @@
-#ifndef ASM_X86__SETUP_H
-#define ASM_X86__SETUP_H
+#ifndef _ASM_X86_SETUP_H
+#define _ASM_X86_SETUP_H
 
 #define COMMAND_LINE_SIZE 2048
 
@@ -102,4 +102,4 @@
 #endif /* __ASSEMBLY__ */
 #endif  /*  __KERNEL__  */
 
-#endif /* ASM_X86__SETUP_H */
+#endif /* _ASM_X86_SETUP_H */