Revert "drm/radeon/kms: disable HDMI audio for now on rv710/rv730"

This commit "disabled" audio on RV710 and RV740 only, leaving RV770 and RV730.
The order is: CHIP_RV770 < CHIP_RV730 < CHIP_RV710 < CHIP_RV740.

It is not needed anway, as we do not even try to enable audio on RV770 and
newer. We call initializing function in r600.c only, not in rv770.c.

If there is something causing green tinges, it's HDMI mode setting for encoder
and I will try to debug that.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>