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

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>