V4L/DVB (6670): V4L: saa7134: tvaudio cleanups

move some tv-audio initialization code out of tvaudio thread,
and call it on resume too.

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>