drm/amd/display: Bypass sink detect when there are no eDPs connected

[How & Why]
Check DC config to determine if there are any eDPs connected. If there
are no eDPs connected, bypass sink detect when querying eDP presence.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Jake Wang <haonan.wang2@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Solomon Chiu <solomon.chiu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>