[media] V4L: sh_mobile_ceu_camera: implement live cropping

PRELIMINARY: break out spinlock changes; consider multiple completing
feames, causing multiple complete() calles.

Add live crop support to the sh_mobile_ceu driver.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>