WiFi : Fix to DHCP to static IP configuration problem

WiFiStateMachine shall update the IP address configuration to
the kernel through NetworkManagementService.This notification
from the kernel is again sent to the connectivity service
through the NetLinkStateTracker and WiFiStateMachine.
Thus ,if the interface is down during this IP address
reconfiguration (for the case of DHCP to Static IP configuration),
Connectivity service shall be notified with old IP address ,NULL(0)
IP address(signifying interface down) and the latest IP address.
This notification was done by updating the IP address using a local
variable , and hence the second notification on the interface down
is over ridden by the last notification , resulting in missed
interface down notification to the connectivity service.This
resulted in failed data connection when IP address is changed from
DHCP to IP on the fly.
Hence ,this gerrit enhances the design and also pass the updated
IP address to the connectivity service.

Change-Id: I50cd0502c5f8259b1325ed68de870b592d96ae22
CRs-Fixed: 750277