V4L/DVB (7976): I2S on for MPEG of saa7134_empress

Rework saa7134_enable_i2s function. Add vendor specific data.
Add definition for I2S audio output control register.

Signed-off-by: Beholder Intl. Ltd. Dmitry Belimov <d.belimov@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>