zink: add VK_BUFFER_USAGE_INDEX_BUFFER_BIT to vertex buffer creation

these can be mixed vertex/index buffers, and there's not really any way
to know in advance

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7132>
1 file changed