Revert "mm: slub: Default slub_max_order to 0"

This reverts commit 115ea4950fd0fac52a55f62eacd363c5b32ee34e.
Revert "slub: fix a memory leak in get_partial_node()"

This reverts commit 3e39adbd1f4d34e13c574e0318776a549e0006cf.