V4L/DVB (12160): soc-camera: fix missing clean up on error path

If soc_camera_init_user_formats() fails in soc_camera_probe(), we have to call
client's .remove() method to unregister the video device.

Reported-by: Kuninori Morimoto <morimoto.kuninori@renesas.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>