efi: app: Avoid switching exception levels on ARM

The EFI app runs under the environment provided to it and is not allowed
to change the exception level. Remove this call for the app.

Signed-off-by: Simon Glass <sjg@chromium.org>

lib/efi_client/app_run.c

@@ -31,7 +31,8 @@ static efi_status_t do_bootefi_exec(efi_handle_t handle, void *load_options)
 	efi_status_t ret;
 
 	/* On ARM switch from EL3 or secure mode to EL2 or non-secure mode */
-	switch_to_non_secure_mode();
+	if (!IS_ENABLED(CONFIG_EFI_APP))
+		switch_to_non_secure_mode();
 
 	/* TODO(sjg@chromium.org): Set watchdog */