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/debugreg.h b/arch/x86/include/asm/debugreg.h
index ecb6907..3ea6f37 100644
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -1,5 +1,5 @@
-#ifndef ASM_X86__DEBUGREG_H
-#define ASM_X86__DEBUGREG_H
+#ifndef _ASM_X86_DEBUGREG_H
+#define _ASM_X86_DEBUGREG_H
 
 
 /* Indicate the register numbers for a number of the specific
@@ -67,4 +67,4 @@
 #define DR_LOCAL_SLOWDOWN (0x100)   /* Local slow the pipeline */
 #define DR_GLOBAL_SLOWDOWN (0x200)  /* Global slow the pipeline */
 
-#endif /* ASM_X86__DEBUGREG_H */
+#endif /* _ASM_X86_DEBUGREG_H */