Only enable data for one SIM in DSDS.

Only enable mobile data for one SIM for simplicity. Which means When
turning on mobile data on non-default sub, pop a notification to user
that it will turn off data of the other one.

Bug: 120515679
Test: manual and unittest
Change-Id: I7c190bb70d771b7f280c246038a380e4fc7338a3
3 files changed