ath79: add support for Buffalo WZR-600DHP

The hardware of this device seems to be identical to WZR-HP-AG300H.
It was already implemented as a clone in ar71xx.

Specification:
- 680 MHz CPU (Qualcomm Atheros AR7161)
- 128 MiB RAM
- 32 MiB Flash
- WiFi 5 GHz a/n
- WiFi 2.4 GHz b/g/n
- 5x 1000Base-T Ethernet
- 1x USB 2.0

Installation of OpenWRT from vendor firmware:
- Connect to the Web-interface at http://192.168.11.1
- Go to “Administration” → “Firmware Upgrade”
- Upload the OpenWrt factory image

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/ath79/image/generic.mk

@@ -333,16 +333,26 @@ define Device/buffalo_bhr-4grv2
 endef
 TARGET_DEVICES += buffalo_bhr-4grv2
 
-define Device/buffalo_wzr-hp-ag300h
+define Device/buffalo_wzr_ar7161
   $(Device/buffalo_common)
   SOC := ar7161
-  DEVICE_MODEL := WZR-HP-AG300H
   BUFFALO_PRODUCT := WZR-HP-AG300H
   DEVICE_PACKAGES := kmod-usb-ohci kmod-usb2 kmod-usb-ledtrig-usbport \
 	kmod-leds-reset kmod-owl-loader
   IMAGE_SIZE := 32320k
   SUPPORTED_DEVICES += wzr-hp-ag300h
 endef
+
+define Device/buffalo_wzr-600dhp
+  $(Device/buffalo_wzr_ar7161)
+  DEVICE_MODEL := WZR-600DHP
+endef
+TARGET_DEVICES += buffalo_wzr-600dhp
+
+define Device/buffalo_wzr-hp-ag300h
+  $(Device/buffalo_wzr_ar7161)
+  DEVICE_MODEL := WZR-HP-AG300H
+endef
 TARGET_DEVICES += buffalo_wzr-hp-ag300h
 
 define Device/buffalo_wzr-hp-g302h-a1a0