V4L/DVB (12304): cx23885: Remove hardcoded gpio bits from the encoder driver

The encoder driver has hardcoded GPIO bits set for the HVR1800, regardless
of whether it's being used by a HVR1800 or not. I've implemented some generic
GPIO manipulation routines and I'm calling them only when appropriate.

Signed-off-by: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>