SystemUI: Check current data subscription when updating signal cluster

* Checking connected and data state is insufficient when updating the
  signal cluster, for multi-SIM use we need to check whether the current
  signal controller has the data subscription as well, otherwise it's
  possible for both clusters to display the data tech simultaneously.

REF: KIPPER-702
Change-Id: I1dd2994271df2c42deb8e9aeb7c01798a6cfd2ca