V4L/DVB: dm1105: use macro for read/write registers

This is for better readability and smaller size of code lines.
Also it is for future improvements like GPIO handling.

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