drm/amdgpu: correct the cu count for gfx v11

Correct the algorithm of active CU to skip disabled
sa for gfx v11.

Signed-off-by: Likun Gao <Likun.Gao@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org