efi_loader: bump UEFI specification number to 2.8

We are implementing UEFI variable RuntimeServicesSupported and set the
unimplemented runtime functions return EFI_UNSUPPORTED as described in UEFI
specification 2.8. So let's also advertise this specification version in
our system table.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Alexander Graf <agraf@csgraf.de>
diff --git a/include/efi_api.h b/include/efi_api.h
index a36ecec..d4f32db 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -23,8 +23,8 @@
 #include <asm/setjmp.h>
 #endif
 
-/* UEFI spec version 2.7 */
-#define EFI_SPECIFICATION_VERSION (2 << 16 | 70)
+/* UEFI spec version 2.8 */
+#define EFI_SPECIFICATION_VERSION (2 << 16 | 80)
 
 /* Types and defines for EFI CreateEvent */
 enum efi_timer_delay {