V4L/DVB: cx23885: Convert cx23885-input to use new in kernel IR pulse decoders

Convert the cx23885 driver to use the new in kernel IR pulse
decoders for the integrated CX2388[578] IR controllers.  Rip out a lot
of RC-5 decoding related code in the process and rename some variables
for clarity or to more accurately describe their usage.

Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>