ar71xx: improve support for TP-Link CPE510 v2

This fixes commit bae927c551 ("ar71xx: add support for TP-LINK CPE510
V2.0") where the support for this device wasn't optimal.

Device support for the CPE510v2 so far has been a hack to enable
flashing with CPE510v1 images. Those even have different hardware (e.g.
additional ethernet port).

With this patch, we provide proper support for this device in ar71xx.

Installation:
- Flash factory image through stock firmware WEB UI or through TFTP
- To get to TFTP recovery just hold reset button while powering on
  for around 4-5 seconds and release.
- Rename factory image to recovery.bin
- Stock TFTP server IP: 192.168.0.100
- Stock device TFTP address: 192.168.0.254

Fixes: bae927c551 ("ar71xx: add support for TP-LINK CPE510 V2.0")
Signed-off-by: Andrew Cameron <apcameron@softhome.net>
[Rebased onto revert commit, changed comments in mach-cpe510.c,
changed commit title and description, fixed eth0 MAC address,
removed eth1 initialization]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
[squashed revert, added fixes tag]
Signed-off-by: Petr Štetiar <ynezz@true.cz>

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

@@ -255,6 +255,7 @@ cpe210|\
 cpe210-v2|\
 cpe210-v3|\
 cpe510|\
+cpe510-v2|\
 wbs210|\
 wbs510)
 	ucidef_set_rssimon "wlan0" "200000" "1"
@@ -265,7 +266,8 @@ wbs510)
 
 	case "$board" in
 	cpe210-v2|\
-	cpe210-v3)
+	cpe210-v3|\
+	cpe510-v2)
 		ucidef_set_led_netdev "lan" "LAN" "tp-link:green:lan0" "eth0"
 		;;
 	*)

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

@@ -76,6 +76,7 @@ ar71xx_setup_interfaces()
 	cf-e380ac-v2|\
 	cpe210-v2|\
 	cpe210-v3|\
+	cpe510-v2|\
 	dr342|\
 	eap120|\
 	eap300v2|\