media: cx18: reorder fmt_vid_cap functions in cx18-ioctl.c

No actual code changed, this just reorders functions so that the
g/try/s_fmt_vid_cap functions are all together rather than mixed in
with the vbi format functions.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>