Some operator supports multiple VILTE,
both two SIM cards can make VILTE call.
We need to record VILTE data to different interface.
Now NetworkStatsService has only one VILTE data
interface: "vt_data0". All VILTE data stats will
be recorded in this interface.
Bug: 130871087
Test: NetworkStatsServiceTest#testDualVilteProviderStats
Change-Id: I000ec756827bc42cac88dd0a2ca6b7999252357e