drm/amd/display: Limit DCN32 8 channel or less parts to DPM1 for FPO

- Due to hardware related QoS issues, we need to limit certain
  SKUs with less memory channels to DPM1 and above.
- At DPM0 + workload running, the urgent return latency can
  exceed 15us (the expected maximum is 4us) which results in underflow

Cc: stable@vger.kernel.org
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Saaem Rizvi <SyedSaaem.Rizvi@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alvin Lee <Alvin.Lee2@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>