dma-buf/fence: Sparse wants __rcu on the object itself

In order to silence sparse in dma_fence_get_rcu_safe(), we need to mark
the incoming fence object as being RCU protected and not the pointer to
the object.

Cc: Dave Airlie <airlied@redhat.com>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Cc: linaro-mm-sig@lists.linaro.org
Cc: linux-media@vger.kernel.org
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171102200336.23347-3-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
[vsyrjala: s/silent/silence/ in commit message]
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

include/linux/dma-fence.h

@@ -242,7 +242,7 @@ static inline struct dma_fence *dma_fence_get_rcu(struct dma_fence *fence)
  * The caller is required to hold the RCU read lock.
  */
 static inline struct dma_fence *
-dma_fence_get_rcu_safe(struct dma_fence * __rcu *fencep)
+dma_fence_get_rcu_safe(struct dma_fence __rcu **fencep)
 {
 	do {
 		struct dma_fence *fence;