drm/radeon: fix active cu count for SI and CIK

This fixes the CU count reported to userspace for
OpenCL.

bug:
https://bugzilla.kernel.org/show_bug.cgi?id=82581



Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Cc: stable@vger.kernel.org