V4L/DVB (6884): Add support for the Xceive xc5000 silicon tuner

This is an all formats tuner, QAM, ATSC, DVB-T and others.
Only ATSC and QAM have been tested.

Signed-off-by: Steven Toth <stoth@hauppauge.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>