drm/etnaviv: 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> Cc: stable@vger.kernel.org Cc: Lucas Stach <l.stach@pengutronix.de> Cc: Russell King <linux+etnaviv@armlinux.org.uk> Cc: Christian Gmeiner <christian.gmeiner@gmail.com> Cc: etnaviv@lists.freedesktop.org Signed-off-by: Lucas Stach <l.stach@pengutronix.de>