drm/radeon: fix the audio dpms callbacks

Don't touch the audio enable bits as these are already
handled in display detection.  Enable the hdmi secondary
streams in hdmi enable to match dp.  Rename dp dpms
callback to be consistent with hdmi.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=89327
https://bugzilla.kernel.org/show_bug.cgi?id=93921

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>