ramips: fix GL-inet GL-MT300N-V2 WAN/LAN MAC address

Correct MAC address lookup to appropriate offset based on vendor
source.

Override the WAN MAC to use the same address as LAN. The switch driver
increments the base MAC address for the WAN vlan but the stock firmware
uses the same MAC address for all interfaces.

Based on vendor source commit
https://github.com/domino-team/lede-1701/commit/efb0518

Signed-off-by: John Marrett <johnf@zioncluster.ca>

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

@@ -381,6 +381,9 @@ ramips_setup_macs()
 	e1700)
 		wan_mac=$(mtd_get_mac_ascii config WAN_MAC_ADDR)
 		;;
+	gl-mt300n-v2)
+		wan_mac=$(mtd_get_mac_binary factory 4)
+		;;
 	hc5*61|\
 	hc5661a|\
 	hc5962)

target/linux/ramips/dts/GL-MT300N-V2.dts

@@ -80,7 +80,7 @@
 };
 
 &ethernet {
-	mtd-mac-address = <&factory 0x4000>;
+	mtd-mac-address = <&factory 0x4>;
 };
 
 &wmac {