V4L/DVB (5775): Alsa fix for SAA7134 based "KNC One TV-Station DVR" card

Sound recording doesn't work for this card because ACNI and ACPF
are not set before snd_card_saa7134_capture_prepare(). As a result
timeout occurs. These registers aren't poked because thread
never gets wake up signal. ACNI initialization is done in the
thread.
Sound is muted when capture stops. Shouldn't be because it may
be used during TV playback.

Signed-off-by: Rafal Bilski <rafalbilski@interia.pl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>