Telephony: Call forwarding icon is shown after powerup.

If call forwarding was enabled, then the call forwarding
icon should be shown after the phone has powered down and
powered-up. Added a preference parameter to store the icon
status, in case it is not updated correctly by the network
operator.

CRs-Fixed: 275722

Change-Id: I06ae47c8decae64807de78461382ca746900a8dd