[media] Convert Wideview WT220 DVB USB driver to rc-core

Converts the dtt200u DVB USB driver over to the rc-core
infrastructure for its handling of IR remotes. This device can receive
generic NEC / NEC Extended signals and the switch to the newer core
enables the easy use of tools such as ir-keytable to modify the active
key map.

Signed-off-by: Jonathan McDowell <noodles@earth.li>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>