V4L/DVB (6144): Fix mux setup for composite sound on AverTV 307

V4L/DVB (6144): Fix mux setup for composite sound on AverTV 307

Right now the composite sound input doesn't work on AverTV 307 because of
the wrong mux setup.  The composite sound is routed via an external
4channel multiplexer controlled by GPIO, while the code assumes an internal
multiplexer instead.

Presumably this was a copy/paste error, and noone have ever tested the
functionality.

With the attached patch it works properly, which gives me an ability to
finally watch the cable TV under linux.

Signed-off-by: Stas Sergeev <stsp@aknet.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Nickolay V. Shmyrev <nshmyrev@yandex.ru>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>