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/cpu.h b/arch/x86/include/asm/cpu.h
index 83a1150..bae482d 100644
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -1,5 +1,5 @@
-#ifndef ASM_X86__CPU_H
-#define ASM_X86__CPU_H
+#ifndef _ASM_X86_CPU_H
+#define _ASM_X86_CPU_H
 
 #include <linux/device.h>
 #include <linux/cpu.h>
@@ -17,4 +17,4 @@
 #endif
 
 DECLARE_PER_CPU(int, cpu_state);
-#endif /* ASM_X86__CPU_H */
+#endif /* _ASM_X86_CPU_H */