x86: Don't use magic strings for EFI loader signature

Introduce a symbol, EFI_LOADER_SIGNATURE instead of using the magic
strings, which also helps to reduce the amount of ifdeffery.

Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/1318848017-12301-1-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index b8d8bfc..26d8c18 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -3,6 +3,8 @@
 
 #ifdef CONFIG_X86_32
 
+#define EFI_LOADER_SIGNATURE	"EL32"
+
 extern unsigned long asmlinkage efi_call_phys(void *, ...);
 
 #define efi_call_phys0(f)		efi_call_phys(f)
@@ -35,6 +37,8 @@
 
 #else /* !CONFIG_X86_32 */
 
+#define EFI_LOADER_SIGNATURE	"EL64"
+
 extern u64 efi_call0(void *fp);
 extern u64 efi_call1(void *fp, u64 arg1);
 extern u64 efi_call2(void *fp, u64 arg1, u64 arg2);