Update network mode in shared preference

Shared preference should be up to date as this is used
to set to modem once data subscription is changed.

Updating the shared preference when ever user modified the
network type to make sure that latest user prefernce will
be set to modem.

Change-Id: I0b9b75f1f6b91c1b4209c95394c48781f3da3503
CRs-Fixed: 659599