Don't hide the mobile type id if it doesn't change

_Someone_ thought it would be a good idea to hide the mobile type
indicator if it hadn't changed from the last state. Better to not do
that.

Also removed an unused method in StatusBarIconControllerImpl.

Test: Reboot device with wifi off; data type indicator should show up
eventually; i.e., visual
Fixes: 77581445

Change-Id: I47a0c868b0e332c11e206b8c043a532bcbf10130