etnaviv: update resource status after flushing

Currently piglit spec@arb_occlusion_query@occlusion_query_conform
spins for ever as the resource status is never reset. See
etna_hw_get_query_result(..) for more details.

Fixes: 1456aa61 ("etnaviv: Rework resource status tracking")
CC: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Tested-by: Marek Vasut <marex@denx.de>
(cherry picked from commit 6e75f217)