chain->base.present_mode is unset at this point, ie. it's
zero-initialized. VK_PRESENT_MODE_IMMEDIATE_KHR happens to be 0,
so the WSI will attempt to use tearing-control on compositors that
don't support it.
Signed-off-by: Simon Ser <contact@emersion.fr>
Fixes: 5ceba97c2e ("vulkan/wsi/wayland: add support for IMMEDIATE")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24885>