[media] media: i2c: mt9p031: add support for asynchronous probing

Both synchronous and asynchronous mt9p031 subdevice probing
is supported by this patch.

Signed-off-by: Lad, Prabhakar <[e-mail]>
Signed-off-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/i2c/mt9p031.c

···
 #include <linux/videodev2.h>
 
 #include <media/mt9p031.h>
+#include <media/v4l2-async.h>
 #include <media/v4l2-ctrls.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-subdev.h>
···
 	}
 
 	ret = mt9p031_clk_setup(mt9p031);
+	if (ret)
+		goto done;
+
+	ret = v4l2_async_register_subdev(&mt9p031->subdev);
 
 done:
 	if (ret < 0) {
···
 	struct mt9p031 *mt9p031 = to_mt9p031(subdev);
 
 	v4l2_ctrl_handler_free(&mt9p031->ctrls);
-	v4l2_device_unregister_subdev(subdev);
+	v4l2_async_unregister_subdev(subdev);
 	media_entity_cleanup(&subdev->entity);
 	mutex_destroy(&mt9p031->power_lock);