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/mutex_64.h b/arch/x86/include/asm/mutex_64.h
index 918ba21..68a87b0 100644
--- a/arch/x86/include/asm/mutex_64.h
+++ b/arch/x86/include/asm/mutex_64.h
@@ -6,8 +6,8 @@
  *
  *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  */
-#ifndef ASM_X86__MUTEX_64_H
-#define ASM_X86__MUTEX_64_H
+#ifndef _ASM_X86_MUTEX_64_H
+#define _ASM_X86_MUTEX_64_H
 
 /**
  * __mutex_fastpath_lock - decrement and call function if negative
@@ -97,4 +97,4 @@
 		return 0;
 }
 
-#endif /* ASM_X86__MUTEX_64_H */
+#endif /* _ASM_X86_MUTEX_64_H */