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/efi.h b/arch/x86/include/asm/efi.h
index 313438e..a2e545c 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -1,5 +1,5 @@
-#ifndef ASM_X86__EFI_H
-#define ASM_X86__EFI_H
+#ifndef _ASM_X86_EFI_H
+#define _ASM_X86_EFI_H
 
 #ifdef CONFIG_X86_32
 
@@ -107,4 +107,4 @@
 #define efi_call6(_f, _a1, _a2, _a3, _a4, _a5, _a6)	(-ENOSYS)
 #endif /* CONFIG_EFI */
 
-#endif /* ASM_X86__EFI_H */
+#endif /* _ASM_X86_EFI_H */