x86: drop double underscores from header guards

Drop double underscores from header guards in arch/x86/include.  They
are used inconsistently, and are not necessary.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/include/asm/xen/interface.h b/arch/x86/include/asm/xen/interface.h
index 6cfc896..e8506c1 100644
--- a/arch/x86/include/asm/xen/interface.h
+++ b/arch/x86/include/asm/xen/interface.h
@@ -6,8 +6,8 @@
  * Copyright (c) 2004, K A Fraser
  */
 
-#ifndef _ASM_X86_XEN__INTERFACE_H
-#define _ASM_X86_XEN__INTERFACE_H
+#ifndef _ASM_X86_XEN_INTERFACE_H
+#define _ASM_X86_XEN_INTERFACE_H
 
 #ifdef __XEN__
 #define __DEFINE_GUEST_HANDLE(name, type) \
@@ -172,4 +172,4 @@
 #define XEN_CPUID          XEN_EMULATE_PREFIX "cpuid"
 #endif
 
-#endif /* _ASM_X86_XEN__INTERFACE_H */
+#endif /* _ASM_X86_XEN_INTERFACE_H */