dma-buf: balance refcount inbalance

The debugfs take reference on fence without dropping them.
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: Stéphane Marchesin <marcheu@chromium.org>
Cc: stable@vger.kernel.org
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20181206161840.6578-1-jglisse@redhat.com

drivers/dma-buf/dma-buf.c

@@ -1068,6 +1068,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 				   fence->ops->get_driver_name(fence),
 				   fence->ops->get_timeline_name(fence),
 				   dma_fence_is_signaled(fence) ? "" : "un");
+			dma_fence_put(fence);
 		}
 		rcu_read_unlock();