[media] mceusb: improve ir data buffer parser

Switch to a state machine that properly handles all incoming urb data
packets, and reads much cleaner and corrects some minor parsing errors
that were hindering decode on cx231xx/Polaris integrated IR. Also tested
with four different mceusb variants, and works perfectly with all of
them (at least for the rc6a mce remotes).

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>