workqueue: Move wq_pod_init() below workqueue_init()

wq_pod_init() is called from workqueue_init() and responsible for
initializing unbound CPU pods according to NUMA node. Workqueue is in the
process of improving affinity awareness and wants to use other topology
information to initialize unbound CPU pods; however, unlike NUMA nodes,
other topology information isn't yet available in workqueue_init().

The next patch will introduce a later stage init function for workqueue
which will be responsible for initializing unbound CPU pods. Relocate
wq_pod_init() below workqueue_init() where the new init function is going to
be located so that the diff can show the content differences.

Just a relocation. No functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>