drm/msm: Expose our reservation object when exporting a dmabuf.

drm/msm: Expose our reservation object when exporting a dmabuf.

Without this, polling on the dma-buf (and presumably other devices
synchronizing against our rendering) would return immediately, even
while the BO was busy.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Cc: Rob Clark <robdclark@gmail.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Rob Clark <robdclark@gmail.com>