Create a common allocator for first chunk initialization,
pcpu_alloc_first_chunk. Comments for this function will be added in a
later patch once the bitmap allocator is added.
Signed-off-by: NDennis Zhou <dennisszhou@gmail.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NTejun Heo <tj@kernel.org>