V4L/DVB (6735): Reorder functions to make easier to compare with the …

…previous code

After this patch, the order of the functions will be the same as before the
patch converting the driver to user video_ioctl2. This makes easier to diff
between the previous version and the newer one.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>