with dpm enabled, need to get active crtcs in dc/no-dc mode.

caused by
'commit ebb649667a31 ("drm/amdgpu: Set pm_display_cfg in non-dc mode")'
Reviewed-by: NHuang Rui <ray.huang@amd.com>
Signed-off-by: NRex Zhu <Rex.Zhu@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>