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/mca.h b/arch/x86/include/asm/mca.h
index 60d1ed2..eedbb6c 100644
--- a/arch/x86/include/asm/mca.h
+++ b/arch/x86/include/asm/mca.h
@@ -1,8 +1,8 @@
 /* -*- mode: c; c-basic-offset: 8 -*- */
 
 /* Platform specific MCA defines */
-#ifndef ASM_X86__MCA_H
-#define ASM_X86__MCA_H
+#ifndef _ASM_X86_MCA_H
+#define _ASM_X86_MCA_H
 
 /* Maximal number of MCA slots - actually, some machines have less, but
  * they all have sufficient number of POS registers to cover 8.
@@ -40,4 +40,4 @@
  */
 #define MCA_NUMADAPTERS (MCA_MAX_SLOT_NR+3)
 
-#endif /* ASM_X86__MCA_H */
+#endif /* _ASM_X86_MCA_H */