radeon/audio: enable DP audio

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Slava Grigorev <slava.grigorev@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --cc drivers/gpu/drm/radeon/atombios_encoders.c
Simple merge

diff --cc drivers/gpu/drm/radeon/dce6_afmt.c
Simple merge

diff --cc drivers/gpu/drm/radeon/evergreen_hdmi.c
Simple merge

diff --cc drivers/gpu/drm/radeon/evergreen_reg.h
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_audio.c
Simple merge