zink: rework in-use batch states hash table to be a singly-linked list

zink: rework in-use batch states hash table to be a singly-linked list

it was useful to have this be a hash table back before timeline semaphores when
the batch state needed to be looked up every time to determine resource busy state,
but now in the modern world, this is almost never happening, and storing them like
this is actually worse for performance, so flatten it out into a simpler list

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13265>