ramips: add support for unbranded XDX-RN502J board

This patch adds support for routers using a PCB marked XDX-RN502J
V2.0, such as some unbranded routers like this:

http://www.mediafire.com/?8acv87h6snn9fj6
http://www.mediafire.com/?do7xonw7scor4kn
http://www.mediafire.com/?1ad49zvx3e7jyix
http://www.mediafire.com/?i46cqiq66maa197

http://www.aliexpress.com/product-fm/516397994-Free-Shipping-300M-3G-WAN-Wireless-N-WiFi-USB-AP-Router-2-Antennas-wholesalers.html

some reports also state the Aceex 22Y uses the same board.

more information can be found in the following openwrt forum post
https://forum.openwrt.org/viewtopic.php?id=34878

[juhosg: fix checkpatch warnings, use the GENERIC_4M template]

Signed-off-by: bruno schwander <bruno@tinkerbox.org>

SVN-Revision: 30809

target/linux/ramips/base-files/lib/preinit/06_set_iface_mac

@@ -28,7 +28,8 @@ preinit_set_mac_address() {
 	nbg-419n |\
 	omni-emb |\
 	w502u    |\
-	wr6202)
+	wr6202 |\
+	xdxrn502j)
 		mac=$(ramips_get_mac_binary factory 40)
 		ifconfig eth0 hw ether $mac 2>/dev/null
 		;;

target/linux/ramips/base-files/lib/ramips.sh

@@ -143,6 +143,9 @@ ramips_board_name() {
 	*"AWB WR6202")
 		name="wr6202"
 		;;
+	*"XDX RN502J")
+		name="xdxrn502j"
+		;;
 	*)
 		name="generic"
 		;;