V4L/DVB: ir-core: remove ir-functions usage from cx231xx

Convert drivers/media/video/cx231xx/cx231xx-input.c to not
rely on ir-functions.c.

(I do not have the hardware so I can only compile test this)

Signed-off-by: David Härdeman <david@hardeman.nu>
Cc: Srinivasa Deevi <srinivasa.deevi@conexant.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>