Merge ImsSs in the case the voice registration is OUT_OF_SERVICE

For some vendors, the modem does not report a voice registration
status of IN_SERVICE for LTE if there is no CSFB voice registration
available. In this case, ServiceState#getServiceState() was returning
OUT_OF_SERVICE even though calling was available through IMS.

Instead, always override the voice registration state with the
IMS data registration state if the voice registration is
OUT_OF_SERVICE for CS.

Bug: 139844125
Test: atest CtsTelephonyTestCases; atest FrameworksTelephonyTests
Change-Id: I44ba5525fdec1e8dfa9e61846b93d1db2871fc4f