netifd: dhcp proto convert release to norelease

Change dhcp no/release on shutdown to 'norelease' uci option to match
existing proto dhcpv6 usage.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Acked-by: Hans Dedecker <dedeckeh@gmail.com>

package/network/config/netifd/files/etc/uci-defaults/14_migrate-dhcp-release

@@ -0,0 +1,23 @@
+. /lib/functions.sh
+
+migrate_release() {
+	local config="$1"
+	local proto
+	local release
+
+	config_get proto "$config" proto
+	config_get release "$config" release
+
+	[ "$proto" = "dhcp" ] && [ -n "$release" ] && {
+		norelease="$((!$release))"
+		uci_set network "$config" norelease "$norelease"
+		uci_remove network "$config" release
+	}
+
+}
+
+config_load network
+config_foreach migrate_release interface
+commit network
+
+exit 0