device: restart DHCP when the MAC changes

If the MAC changes there is the possibility that the DHCP client will
not be able to renew the address because it uses the old MAC as
CHADDR. Depending on the implementation, the DHCP server might use
CHADDR (so, the old address) as the destination MAC for DHCP replies,
and those packets will be lost.

To avoid this problem, restart the DHCP client when the MAC changes.
61 jobs for bg/restart-dhcp-on-mac-change in 34 minutes and 14 seconds (queued for 4 seconds)