drm/radeon: fix hdmi audio on DCE3.0/3.1 asics

These asics seem to use a mix of the DCE2.x and
DCE3.2 audio interfaces despite what the register spec
says.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=69729
https://bugs.freedesktop.org/show_bug.cgi?id=69671



Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org