drm/amdgpu: fix bug in fence driver fini

Using wrong counter for walking fences. Fixes
a crash when unloading the driver.

Signed-off-by: Monk Liu <[e-mail]>
Reviewed-by: Christian König <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 		amd_sched_fini(&ring->sched);
 		del_timer_sync(&ring->fence_drv.fallback_timer);
 		for (j = 0; j <= ring->fence_drv.num_fences_mask; ++j)
-			fence_put(ring->fence_drv.fences[i]);
+			fence_put(ring->fence_drv.fences[j]);
 		kfree(ring->fence_drv.fences);
 		ring->fence_drv.initialized = false;
 	}