ath79: fix MAC address setup for TP-Link TL-WDR3600/TL-WDR4300

The current ethernet MAC address setup of TL-WDR4300 board is different
from the setup of stock firmware:

OpenWrt: lan = label_mac -2, wan = label_mac -2
  stock: lan = label_mac,    wan = label_mac +1

The full address assignment is as follows:
LAN  label
WAN  label + 1
5G   label
2G   label - 1

This patch changes all devices using TL-WDR4300 board:
TL-WDR3600 v1 (checked on device)
TL-WDR4300 v1 (checked on device)
TL-WDR4300 v1 (IL)

Signed-off-by: Sungbo Eo <mans0n@gorani.run>
[rephrase/extend commit title/message]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/ath79/dts/ar9344_tplink_tl-wdr4300.dtsi

@@ -116,7 +116,6 @@
 	pll-data = <0x06000000 0x00000101 0x00001616>;
 
 	mtd-mac-address = <&uboot 0x1fc00>;
-	mtd-mac-address-increment = <(-2)>;
 
 	phy-mode = "rgmii";
 	phy-handle = <&phy0>;

target/linux/ath79/generic/base-files/etc/board.d/02_network

@@ -390,6 +390,12 @@ ath79_setup_macs()
 		base_mac=$(mtd_get_mac_binary info 0x8)
 		wan_mac=$(macaddr_add "$base_mac" 1)
 		;;
+	tplink,tl-wdr3600-v1|\
+	tplink,tl-wdr4300-v1|\
+	tplink,tl-wdr4300-v1-il)
+		base_mac=$(mtd_get_mac_binary u-boot 0x1fc00)
+		wan_mac=$(macaddr_add "$base_mac" 1)
+		;;
 	trendnet,tew-823dru)
 		lan_mac=$(mtd_get_mac_text mac 0x4)
 		wan_mac=$(mtd_get_mac_text mac 0x18)