ath79: fix swapped LAN/WAN MAC address for Archer C60 v1/v2

The MAC addresses for lan/wan are swapped compared to the vendor
firmware. This adjusts to vendor configuration, which is:

lan   *:7b   label
wan   *:7c   label+1
2.4g  *:7b   label
5g    *:7a   label-1

Only one address is stored in <&mac 0x8>, corresponding to the label.

This has been checked on revisions v1, v2 and v3.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
(cherry picked from commit 88aead0a665dd349af4fb8afcfe1a16cf90515ae)

target/linux/ath79/dts/qca9561_tplink_archer-c6x.dtsi

@@ -91,13 +91,13 @@
 	phy-handle = <&swphy4>;
 
 	mtd-mac-address = <&mac 0x8>;
+	mtd-mac-address-increment = <1>;
 };
 
 &eth1 {
 	status = "okay";
 
 	mtd-mac-address = <&mac 0x8>;
-	mtd-mac-address-increment = <1>;
 };
 
 &wmac {