V4L/DVB (6330): V4L: saa7134: Fix interaction between tvaudio thread and the freezer

make tvaudio thread freezeable, and add proper support for that

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