V4L/DVB (3368): KWorld HardwareMpegTV XPert: update comments

Standard video using the cx88 broadcast decoder is
working, but blackbird isn't working yet, audio is only
working correctly for television mode. S-Video and Composite
are working for video-only, so I have them disabled for now.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>