drm/radeon: fix DAC interrupt handling on DCE5+

DCE5 and newer hardware only has 1 DAC.  Use the correct
offset.  This may fix display problems on certain board
configurations.

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

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

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

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