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_host.h b/arch/x86/include/asm/kvm_host.h
index 411fb8c..65679d0 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -8,8 +8,8 @@
  *
  */
 
-#ifndef ASM_X86__KVM_HOST_H
-#define ASM_X86__KVM_HOST_H
+#ifndef _ASM_X86_KVM_HOST_H
+#define _ASM_X86_KVM_HOST_H
 
 #include <linux/types.h>
 #include <linux/mm.h>
@@ -749,4 +749,4 @@
 int kvm_unmap_hva(struct kvm *kvm, unsigned long hva);
 int kvm_age_hva(struct kvm *kvm, unsigned long hva);
 
-#endif /* ASM_X86__KVM_HOST_H */
+#endif /* _ASM_X86_KVM_HOST_H */