[media] cx231xx: Only register USB interface 1

Interface 0 is used by IR. The current driver starts initializing
on it, finishing on interface 6. Change the logic to only handle
interface 1. This allows another driver (mceusb) to take care of
the IR interface.

Reviewed-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Sri Devi <Srinivasa.Deevi@conexant.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>