ramips: add label MAC address for TP-Link Archer C20i

Current OpenWrt MAC setup:
eth0             &rom 0xf100    :48
eth0.2           eth0+1         :49
wlan0 (5 GHz)    &radio 0x8004  different OUI
wlan1 (2.4 GHz)  &radio 0x4     same OUI as wlan0

Label MAC address corresponds to eth0 (&ethernet).

No additional addresses found in hexdump of rom/radio.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/ramips/dts/mt7620a_tplink_archer-c20i.dts

@@ -9,6 +9,10 @@
 	compatible = "tplink,archer-c20i", "ralink,mt7620a-soc";
 	model = "TP-Link Archer C20i";
 
+	aliases {
+		label-mac-device = &ethernet;
+	};
+
 	chosen {
 		bootargs = "console=ttyS0,115200";
 	};