efi_loader: only evaluate EFI_EXIT()'s ret once

There are a couple spots doing things like:

   return EFI_EXIT(some_fxn(...));

which I handn't noticed before.  With addition of printing return value
in the EFI_EXIT() macro, now the fxn call was getting evaluated twice.
Which we didn't really want.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

include/efi_loader.h

@@ -21,8 +21,9 @@
 	} while(0)
 
 #define EFI_EXIT(ret) ({ \
-	debug("EFI: Exit: %s: %u\n", __func__, (u32)((ret) & ~EFI_ERROR_MASK)); \
-	efi_exit_func(ret); \
+	efi_status_t _r = ret; \
+	debug("EFI: Exit: %s: %u\n", __func__, (u32)(_r & ~EFI_ERROR_MASK)); \
+	efi_exit_func(_r); \
 	})
 
 extern struct efi_runtime_services efi_runtime_services;