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/kvm.h b/arch/x86/include/asm/kvm.h
index ba0dd79..b95162a 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -1,5 +1,5 @@
-#ifndef ASM_X86__KVM_H
-#define ASM_X86__KVM_H
+#ifndef _ASM_X86_KVM_H
+#define _ASM_X86_KVM_H
 
 /*
  * KVM x86 specific structures and definitions
@@ -208,4 +208,4 @@
 struct kvm_pit_state {
 	struct kvm_pit_channel_state channels[3];
 };
-#endif /* ASM_X86__KVM_H */
+#endif /* _ASM_X86_KVM_H */