mediatek: add v4.19 support

Bump the target to v4.19. Add a patch with additional eth driver
fixes/features that MTK provided aswell as the driver for the new mt7530
switch.

Signed-off-by: John Crispin <john@phrozen.org>

target/linux/mediatek/base-files/etc/hotplug.d/iface/99-mtk-lro

@@ -0,0 +1,14 @@
+[ ifup = "$ACTION" ] && {
+	[ -n "$DEVICE" ] && {
+		if [ "$INTERFACE" == "lan" ]; then
+			if [ -f /usr/sbin/ethtool ]; then
+				ifname=eth0
+				lan_ip=`uci -q get network.lan.ipaddr`
+				ethdrv=`ethtool -i $ifname | grep mtk_soc_eth`
+				[ -n "$ethdrv" ] && {
+					ethtool -N $ifname flow-type tcp4 dst-ip $lan_ip loc 0
+				}
+			fi
+		fi
+	}
+}