[media] cx231xx-417: fix g/try_fmt compliance problems

Colorspace, field and priv were not set, and sizeimage was calculated
using the wrong values (dev->ts1.ts_packet_size and dev->ts1.ts_packet_count
can be 0 at module load).

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>