V4L/DVB (11026): sh-mobile-ceu-camera: set field to the value, configured at open()

For the case, that we have to capture with a default format, i.e., when the
user doesn't call S_FMT, we have to use the field value according to the
default, configured at open() time.

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