wifi: renew dynamic IP configuration after roaming
There are some APs that require a DHCP transaction before allowing other traffic. This is meant to improve security by preventing the use of static addresses. Currently we don't renew DHCP after roaming to a new AP and this can lead to broken connectivity with APs that implement the check described above. Also, even if unlikely, the new AP could be in a different layer 3 network and so the old address could be no longer valid.
Renew dynamic IP configuration after we detect the supplicant decided to roam to a new AP. Note that we only trigger a DHCP client restart; the DHCP client already implements the logic to renew the previous address and fall back to a full request in case of NAK or timeout.