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/smp.h b/arch/x86/include/asm/smp.h
index a6afc29..2766021 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -1,5 +1,5 @@
-#ifndef ASM_X86__SMP_H
-#define ASM_X86__SMP_H
+#ifndef _ASM_X86_SMP_H
+#define _ASM_X86_SMP_H
 #ifndef __ASSEMBLY__
 #include <linux/cpumask.h>
 #include <linux/init.h>
@@ -226,4 +226,4 @@
 #endif /* CONFIG_X86_LOCAL_APIC */
 
 #endif /* __ASSEMBLY__ */
-#endif /* ASM_X86__SMP_H */
+#endif /* _ASM_X86_SMP_H */