drm/amd/display: Add check for PState change in DCN32

For pstate change, allow DML to loop through
all possible prefetch combinations so as to
support more display configurations. Set the max
and min prefetch modes to enable the sequence.

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>