API changes for IPv6 MTU support

Change mtu->mtuV4 and add mtuV6 for DataProfile and DataCallResult
Add mtu to RouteInfo and update test

Test: atest FrameworksTelephonyTests
Bug: 146668814
Change-Id: I43c7e088e46e40f38d8114548e0fc4e39d7f91cb
5 files changed