drm/amd/display: allow psr-su/replay for z8

[why]
allow psr-su/replay for z8

Reviewed-by: Muhammad Ahmed <ahmed.ahmed@amd.com>
Reviewed-by: Sung joon Kim <sungjoon.kim@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Charlene Liu <charlene.liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>