vbios lists DVI-I port as VGA and DVI-D.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=47007Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>