Fixes a crash if swapchain free is called before the list is
initialized. This only happens when swapchain init fails, so
it is highly unlikely to happen in practical scenarios.
Fixes dEQP-VK.wsi.wayland.swapchain.simulate_oom.min_image_count.
Fixes: 0d51cd4808 ("wsi/wl: Improve fallback for present_wait.")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10866
Signed-off-by: Hans-Kristian Arntzen <post@arntzen-software.no>
Reviewed-by: Joshua Ashton <joshua@froggi.es>
Tested-by: Iago Toral Quiroga <itoral@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28325>