ipq40xx: glinet-b1300: fix LAN and WAN MAC address assigments

ipq40xx: glinet-b1300: fix LAN and WAN MAC address assigments

When testing the DSA changes with 5.15.60 kernel, I've noticed, that the
MAC addresses are not properly configured, there is single MAC being
used for LAN and WAN interfaces:

 eth0: 94:83:c4:XX:YY:4a (MAC on sticker)
 lan1@eth0: 94:83:c4:XX:YY:4a
 lan2@eth0: 94:83:c4:XX:YY:4a
 wan@eth0: 94:83:c4:XX:YY:4a
 wlan0: 94:83:c4:XX:YY:4a
 wlan1: 94:83:c4:XX:YY:4b

The same config, prior to the DSA conversion:

 lan/eth0: 94:83:c4:XX:YY:4a (MAC on sticker)
 wan/eth1: 94:83:c4:XX:YY:4b
 wlan0: 94:83:c4:XX:YY:4a
 wlan1: 94:83:c4:XX:YY:4b

Settings in ART partition:

 root@OpenWrt:/# hexdump -C /dev/mtd7 | grep '94 83'
 00000000  94 83 c4 XX YY 4a 94 83  c4 0e YY 4b ff ff ff ff  |.....J.....K....|
 00001000  20 2f 8d 8c 01 01 94 83  c4 XX YY 4a 00 00 20 00  | /.........J.. .|
 00005000  20 2f 5a 3a 01 01 94 83  c4 XX YY 4b 00 00 20 00  | /Z:.......K.. .|

So let's fix it by keeping same MAC address assigment as was done before
DSA conversion and while at it, define `label-mac-device` as well.

Signed-off-by: Petr Štetiar <ynezz@true.cz>