Fixed that data not disconnected when mobile data off

Fixed a bug that network agent and data connection used the
same network info, so when the network agent checks old state
and new state, the states are always the same. This caused
DC network agent not unregister from connectivity service.

Test: Manually tested with data on/off
Bug: 148174674
Change-Id: Iaed3f22317f21f7344d103841bc3c6374a31c492