Don't call the node iteration function inside the node table / node
iterate lock.

This causes LORs and deadlocks as some code paths will have the com lock
held when calling ieee80211_iterate_nodes().

Here, the comlock isn't held during the node table and node iteration
locks; and the callback isn't called with any (extra) lock held.

PR: kern/170098
Submitted by: moonlightakkiy@yahoo.ca
MFC after: 4 weeks