dma-buf: dma_fence_put is NULL safe

No need to check.

Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1502141543-13455-2-git-send-email-alexander.deucher@amd.com

drivers/dma-buf/reservation.c

@@ -195,8 +195,7 @@ done:
 	if (old)
 		kfree_rcu(old, rcu);
 
-	if (old_fence)
-		dma_fence_put(old_fence);
+	dma_fence_put(old_fence);
 }
 
 /**
@@ -258,8 +257,7 @@ void reservation_object_add_excl_fence(struct reservation_object *obj,
 		dma_fence_put(rcu_dereference_protected(old->shared[i],
 						reservation_object_held(obj)));
 
-	if (old_fence)
-		dma_fence_put(old_fence);
+	dma_fence_put(old_fence);
 }
 EXPORT_SYMBOL(reservation_object_add_excl_fence);