Don't reset connections switching default->hipri

A usecase is to use hipri to keep alive 3g connections when wifi
is about to be brought up.  They are the same network, so don't
do the reset unless both are down.

This will go away when we get the deferred network downing.

bug:2865630
Change-Id: I07729b7776fe5ea129120c688cf7839a55a7ed95