[media] cx25840: Hauppauge HVR1850 Analog driver support

Adding support for the CX23888 DIF.
Changes regression tested against the HVR1700 and HVR1800.

Split out much of the set and init handling of the cx23885 based
cards into their own functions. Added the DIF initialization code
for each supported IF.

Updated the cx23885 code to correctly initialize cx23888 based
video/audio decoders.

Enabled Closed Caption support for CX23885 based cards during
initialization.

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