drm/amdgpu: fix memory leak in mes self test

The fences associated with mes queue have to be freed
up during amdgpu_ring_fini.

Signed-off-by: Jack Xiao <Jack.Xiao@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c

@@ -390,6 +390,8 @@ void amdgpu_ring_fini(struct amdgpu_ring *ring)
 		amdgpu_bo_free_kernel(&ring->ring_obj,
 				      &ring->gpu_addr,
 				      (void **)&ring->ring);
+	} else {
+		kfree(ring->fence_drv.fences);
 	}
 
 	dma_fence_put(ring->vmid_wait);