Support of LTE Only mode

In CDMA-LTE hybrid mode, the service state is derived based on
CDMA state. However, CDMA radio is off while in LTE only mode
so thre will be no signal bar or data type icon displayed on
the status UI.

This patch handles LTE only mode scenario. The service state
is derived from LTE if CDMA is OOS and LTE only mode is used.

Bug: 5070240
Change-Id: Ie55daaf9eea1b16ca73312ebab208810b145d2bc