greybus: added warning message in case of missing widget

Additional warning message added to notify in case above layer tries to
access widget that is already removed from the list.
Signed-off-by: Vaibhav Agarwal <vaibhav.agarwal@linaro.org>
Reviewed-by: Mark Greer <mark.greer@animalcreek.com>
Signed-off-by: Alex Elder <elder@linaro.org>

drivers/staging/greybus/audio_topology.c

@@ -99,6 +99,8 @@ static int gbaudio_map_widgetname(struct gbaudio_module_info *module,
 		if (!strncmp(widget->name, name, NAME_SIZE))
 			return widget->id;
 	}
+	dev_warn(module->dev, "%s: missing in modules widgets list\n", name);
+
 	return -EINVAL;
 }