Disallow data when QNS switched the preference

When the preference has switched to another transport, do
not allow data setup. This avoid the case that data service
keeps asking telephony to retry while QNS already switched
the preference to another transport.

Test: Manual
Fix: 182899920
Fix: 175399007
Change-Id: I1a0c86a978756d5b05851d939e011010f8f1afc2