drm/amd/display: Skip eDP detection when no sink

drm/amd/display: Skip eDP detection when no sink

[Why & How]
When there is no eDP panel connected and during
s0ix resume, unnecessary eDP power sequence and
HPD happening, resulting in ~2 seconds delay.

Fixed the issue by avoiding link detect for eDP
connection with no sink in dm_resume.

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Saidireddy Yenugu <Saidireddy.Yenugu@amd.com>
Co-developed-by: ThummarDip Kishorbhai <ThummarDip.Kishorbhai@amd.com>
Signed-off-by: ThummarDip Kishorbhai <ThummarDip.Kishorbhai@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>