ar71xx: add support for EnGenius ENS202EXT

EnGenius ENS202EXT is an outdoor wireless access point with
2-port 10/100 switch, detachable antennas and proprietery PoE.

The device is based on Qualcomm/Atheros AR9341 v1.

Specifications:
- 535/400/200 MHz (CPU/DDR/AHB)
- 64 MB of RAM
- 16 MB of FLASH
- UART (J1) header on PCB (unpopulated)
- 2x 10/100 Mbps Ethernet
- 2.4 GHz, up to 26dBm
- 2x external, detachable antennas
- 7x LED, 1x button

Flash instructions:

You have three options:

- Use the vendor firmware upgrade page on the web interface and give
it the factory.img. This is the easiest way to go about it.

- If you have serial access during u-boot, interrupt the normal boot
(any key before timeout) and run 'run failsafe_boot'; this will bring
you to a minimal openwrt luci image on ip 192.168.1.1 useful if you've
bricked the normal firmware.

- Use the vendor's management cli, which can be accessed via telnet
with the same credentials as the web login (default admin:admin), then
issue the following commands:

*** Hi admin, welcome to use cli(V-1.6.7) ***
---========= Commands Help =========---
      stat -- Status
       sys -- System
    wless2 -- 2.4G-Wireless
      mgmt -- Management
      tree -- Tree
      help -- Help
    reboot -- Reboot
ens202ext>mgmt
  Management
---========= Commands Help =========---
     admin -- Administration
     mvlan -- Management VLAN settings
      snmp -- SNMP settings
    backup -- Backup/Restore settings
    autorb -- Auto reboot settings
   fwgrade -- Firmware upgrade
      time -- Time settings
   wifisch -- Wifi schedule
       log -- Log
      diag -- Diagnostics
      disc -- Device Discovery
    logout -- Logout
      help -- Help
      exit -- Exit
ens202ext/mgmt>fwgrade
  Management --> Firmware upgrade
---========= Commands Help =========---
      fwup -- Firmware upgrade
      help -- Help
      exit -- Exit
ens202ext/mgmt/fwgrade>fwup http://web.server/lede-ar71xx-generic-ens202ext-squashfs-factory.bin

Signed-off-by: Marty Plummer <ntzrmtthihu777@gmail.com>

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

@@ -220,6 +220,13 @@ eap300v2)
 	ucidef_set_led_netdev "lan" "LAN" "engenius:blue:lan" "eth0"
 	ucidef_set_led_wlan "wlan" "WLAN" "engenius:blue:wlan" "phy0tpt"
 	;;
+ens202ext)
+	ucidef_set_rssimon "wlan0" "200000" "1"
+	ucidef_set_led_rssi "rssilow" "RSSILOW" "engenius:amber:wlan1" "wlan0" "1"  "100" "0" "13"
+	ucidef_set_led_rssi "rssimedium" "RSSIMEDIUM" "engenius:red:wlan2" "wlan0" "25" "100" "-39" "13"
+	ucidef_set_led_rssi "rssimediumhigh" "RSSIMEDIUMHIGH" "engenius:amber:wlan3" "wlan0" "50" "100" "-59" "13"
+	ucidef_set_led_rssi "rssihigh" "RSSIHIGH" "engenius:green:wlan4" "wlan0" "75" "100" "-79" "13"
+	;;
 f9k1115v2)
 	ucidef_set_led_usbdev "usb2" "USB2" "belkin:green:usb2" "1-1"
 	;;

target/linux/ar71xx/base-files/etc/diag.sh

@@ -175,6 +175,9 @@ get_status_led() {
 	eap300v2)
 		status_led="engenius:blue:power"
 		;;
+	ens202ext)
+		status_led="engenius:amber:power"
+		;;
 	eap7660d)
 		status_led="$board:green:ds4"
 		;;