[media] cx231xx: remove i2c ir stubs

Nobody is ever going to implement an i2c based IR controller on a bridge that
has an onboard universal IR receiver.  This stuff was all copied from em28xx,
which has old enough versions of the chip that some didn't have onboard IR.

Remove the stubs related to i2c based IR (keeping the cx231xx-input code).

Signed-off-by: Devin Heitmueller <dheitmueller@hauppauge.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>