drm/amd/pm: fix get dpm level count for yello carp

For invalid clk types, return -EINVAL to check the return.

Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
Reviewed-by: Yifan Zhang <yifan1.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>