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/vm86.h b/arch/x86/include/asm/vm86.h
index 998bd18..f930360 100644
--- a/arch/x86/include/asm/vm86.h
+++ b/arch/x86/include/asm/vm86.h
@@ -1,5 +1,5 @@
-#ifndef ASM_X86__VM86_H
-#define ASM_X86__VM86_H
+#ifndef _ASM_X86_VM86_H
+#define _ASM_X86_VM86_H
 
 /*
  * I'm guessing at the VIF/VIP flag usage, but hope that this is how
@@ -205,4 +205,4 @@
 
 #endif /* __KERNEL__ */
 
-#endif /* ASM_X86__VM86_H */
+#endif /* _ASM_X86_VM86_H */