drm/amdgpu: Fix display corruption on CI with dpm enabled

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: Huang Rui <ray.huang@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>