V4L/DVB (12165): cx23885: override set_frontend to allow rf input path switching on the HVR1275

Use separate RF input spigots for Antennae and Cable.

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