drm/amd/display: Enabling eDP no power sequencing with DAL feature mask

drm/amd/display: Enabling eDP no power sequencing with DAL feature mask

[Why]
Sometimes, DP receiver chip power-controlled externally by an
Embedded Controller could be treated and used as eDP,
if it drives mobile display. In this case,
we shouldn't be doing power-sequencing, hence we can skip
waiting for T7-ready and T9-ready."

[How]
Added a feature mask to enable eDP no power sequencing feature.

To enable this, set 0x10 flag in amdgpu.dcfeaturemask on
Linux command line.

Signed-off-by: Zhan Liu <zhan.liu@amd.com>
Reviewed-by: Nikola Cornij <Nikola.Cornij@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>