[media] bttv: Add support for Kworld V-Stream Xpert TV PVR878

New board addition. No other changes.

[m.chehab@samsung.com: rebase patch and fix whitespace mangling]
Signed-off-by: Pojar George <geoubuntu@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>