[dhcpcd] Do not fallback to ipv4ll

With the switch to dhcpcd in [1] we are hitting random
issues in our jobs where dhcp server takes some time to
be ready while cirros just use ipv4ll address and don't
retry. With udhcpc it was not the case, also it used
to retry 3 times every 60 seconds before giving up.

Also added wait for ip configuration for 2 minutes
before forking in background.

[1] ded54d
Related-Bug: https://bugs.launchpad.net/neutron/+bug/2045549

src/etc/init.d/S40network

@@ -7,7 +7,7 @@ case "$1" in
   start)
 	printf "Starting network: "
 	/sbin/ifup lo
-	/sbin/dhcpcd
+	/sbin/dhcpcd --noipv4ll -w -t 120
 	[ $? = 0 ] && echo "OK" || echo "FAIL"
 	;;
   stop)