vk_queue_push_submit() takes ownership of the vk_queue_submit object and
potentially passes it to another thread. This fixes a race where, if
the other thread processes and deletes the vk_queue_submit before we get
to checking _mem_signal_temp, we may have a use-after-free.
Fixes: c95b646e23 ("vulkan/queue: Use _mem_signal_temp instead of signal_mem_sync")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/11988
Reviewed-by: Juan A. Suarez <jasuarez@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31597>