We need to check for DVI vs. HDMI when setting up duallink since
HDMI is single link only.  Fixes 4k modes on newer asics.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=75223Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org