[media] imx074: fix error handling for failed async subdevice registration

If v4l2_async_register_subdev() fails, don't skip the clean up.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>