[NAN] TLV utilities iterator - throw correct exception

Make sure that iterator.next() validates that next element exists -
otherwise throw the exception specified by the interface.

Bug: 30096512
Change-Id: I327da433e3f1181e272c81ee503cbe8aab323f7e
(cherry picked from commit 3e5ac12302a78216e706be239dceb5175646bea0)
1 file changed