V4L/DVB: dm1105: use dm1105_dev & dev instead of dm1105dvb

This is for better readability and smaller size of code.
Also it is similar to other drivers.

Signed-off-by: Igor M. Liplianin <liplianin@me.by>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>