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/lguest_hcall.h b/arch/x86/include/asm/lguest_hcall.h
index 8f034ba..4389442 100644
--- a/arch/x86/include/asm/lguest_hcall.h
+++ b/arch/x86/include/asm/lguest_hcall.h
@@ -1,6 +1,6 @@
 /* Architecture specific portion of the lguest hypercalls */
-#ifndef ASM_X86__LGUEST_HCALL_H
-#define ASM_X86__LGUEST_HCALL_H
+#ifndef _ASM_X86_LGUEST_HCALL_H
+#define _ASM_X86_LGUEST_HCALL_H
 
 #define LHCALL_FLUSH_ASYNC	0
 #define LHCALL_LGUEST_INIT	1
@@ -68,4 +68,4 @@
 };
 
 #endif /* !__ASSEMBLY__ */
-#endif /* ASM_X86__LGUEST_HCALL_H */
+#endif /* _ASM_X86_LGUEST_HCALL_H */