drm/amd/display: Refactor eDP PSR codes

We split out PSR config from "global" to "per-panel" config settings.

Tested-by: Mark Broadworth <mark.broadworth@amd.com>
Reviewed-by: Robin Chen <robin.chen@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Ian Chen <ian.chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>