ar71xx: Add eTactica EG-200 support

EG-200 is a DIN rail mountable device with one ethernet port, wifi,
an RS-485 port, and an internal USB attached uSD card reader.

Two leds, "modbus" and "etactica" are managed by userspace applications
in factory firmware.

Flash instruction:
    Original firmware is based on OpenWrt.
    Use sysupgrade image directly in vendor GUI.

Signed-off-by: Karl Palsson <karlp@etactica.com>

target/linux/ar71xx/base-files/etc/board.d/01_leds

@@ -623,6 +623,12 @@ re450)
 	ucidef_set_led_wlan "wlan2g" "WLAN 2.4 GHz" "$board:blue:wlan2g" "phy1tpt"
 	ucidef_set_led_wlan "wlan5g" "WLAN 5 GHz" "$board:blue:wlan5g" "phy0tpt"
 	;;
+rme-eg200)
+        ucidef_set_led_netdev "wan" "WAN" "eg200:red:eth0" "eth0"
+        ucidef_set_led_wlan "wlan" "WLAN" "eg200:red:wlan" "phy0tpt"
+        ucidef_set_led_oneshot "modbus" "Modbus" "eg200:red:modbus" "100" "33"
+        ucidef_set_led_default "etactica" "etactica" "eg200:red:etactica" "ignore"
+        ;;
 rocket-m-ti)
 	ucidef_set_led_rssi "rssiverylow" "RSSIVERYLOW" "ubnt:green:link1" "wlan0" "1" "100" "0" "13"
 	ucidef_set_led_rssi "rssilow" "RSSILOW" "ubnt:green:link2" "wlan0" "26" "100" "-25" "13"

target/linux/ar71xx/base-files/etc/board.d/02_network

@@ -262,7 +262,8 @@ ar71xx_setup_interfaces()
 		ucidef_add_switch "switch0" \
 			"0@eth0" "3:wan" "4:lan"
 		;;
-	cap324)
+	cap324|\
+	rme-eg200)
 		ucidef_set_interface_lan "eth0" "dhcp"
 		;;
 	cpe210|\