Settings: Support cellular data enabled on both SUBs

The property "persist.radio.carrier_mode" is used to control
some carriers have restricting DDS requirement.

If the property is enabled for class a, when user enables
cellular data, do not change DDS to its slot, and do not
disable cellular data on other slot.

Change-Id: I4e730b2d21011334ea0706b8fffa0f0e55e498ff
CRs-Fixed: 1032075