net/netfilter/ipset/ip_set_hash_netiface.c: use rbtree postorder iteration instead...

net/netfilter/ipset/ip_set_hash_netiface.c: use rbtree postorder iteration instead of opencoding

Use rbtree_postorder_for_each_entry_safe() to destroy the rbtree instead
of opencoding an alternate postorder iteration that modifies the tree

Signed-off-by: Cody P Schafer <[email protected]>
Cc: Michel Lespinasse <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Pablo Neira Ayuso <[email protected]>
Cc: Patrick McHardy <[email protected]>
Cc: Jozsef Kadlecsik <[email protected]>
Cc: "David S. Miller" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>