drm/amdgpu: use exiting amdgpu_ctx_total_num_entities function

simplify driver code.

Signed-off-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
1 file changed