drm/amd/display: Determine DVI-I connector type (v2)

drm/amd/display: Determine DVI-I connector type (v2)

DC determines the DRM connector type based on the
signal type, which becomes problematic when a connector may
support different signal types, such as DVI-I.
With this patch, it is now determined according to the actual
connector type for DVI-D and DVI-I connectors.

Also set the HPD (hotplug detection) flag for DVI-I connectors
to prevent regressing their digital functionality, which has
been already working.

A subsequent commit will also implement polling for DVI-I.

v2:
Only use connector type for DVI to prevent regressions
for other signal types.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>