drm/amd/display: Refactor edp panel power sequencer(PPS) codes

[Why & How]
Move extra panel power sequencer settings into panel_cofig struct.

Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Ian Chen <ian.chen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>