IPv6: allow the same prefix routing entries for link local

Allowing creating multiple link-local routes in the same table, so we can make IPv6
work on all interfaces in the local_network table.

Bug: 126063997
Test: * enable hotspot & usb tethering
      * use ping6 to verify link local in both side of hotspot/usb
      tethering

Change-Id: Ibe897004bd72bc88744c4bbac44ca512c0482f3b
1 file changed