Bluetooth: Added Shared Preferences to restore tethering preference

Added a Shared Preferences to have the tethering preference persist,
The value is stored while changing the tethering preference by user
and tethering preference will be restored based on the value(last
saved tethering preference) while starting the PAN service.
from QCOM
Change-Id: I468564a51ff17dfdf1b95a532fa429477db0da15
1 file changed