New out-of-service RSSI.

This creates (well, restores, since we had this until
Honeycomb) a user-visible state for "no service" that is
distinguishable from "very very weak service" (less than one
bar).

Bug: 5775939
Change-Id: Idd08b1a9411d5d94e4d7a97fa7f3ffd92b8113a6