Driver for Kworld UB499-2T (id 1b80:e409)

The device driver has been named it913x, so that support for other family members
can be added later.

TODOs
Firmware support for other it913x devices.
Remote control support, there are two known types.
Signed-off-by: NMalcolm Priestley <tvboxspy@gmail.com>
[mchehab@redhat.com: Fix a merge conflict]
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>