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/proto.h b/arch/x86/include/asm/proto.h
index 6e89e8b..d6a22f9 100644
--- a/arch/x86/include/asm/proto.h
+++ b/arch/x86/include/asm/proto.h
@@ -1,5 +1,5 @@
-#ifndef ASM_X86__PROTO_H
-#define ASM_X86__PROTO_H
+#ifndef _ASM_X86_PROTO_H
+#define _ASM_X86_PROTO_H
 
 #include <asm/ldt.h>
 
@@ -29,4 +29,4 @@
 #define round_up(x, y) (((x) + (y) - 1) & ~((y) - 1))
 #define round_down(x, y) ((x) & ~((y) - 1))
 
-#endif /* ASM_X86__PROTO_H */
+#endif /* _ASM_X86_PROTO_H */