ath79: add support for Buffalo BHR-4GRV2

Buffalo BHR-4GRV2 is a wired router, based on Qualcomm Atheros
QCA9558.
Ported from ar71xx target.

Specification:

- Qualcomm Atheros QCA9558
- 64 MB of RAM
- 16 MB of Flash
- 5x 10/100/1000 Ethernet
  - QCA8337N
- 4x LEDs, 2x keys
- UART header on PCB
  - Vcc, TX, RX, GND from LED side
  - 115200n8

Flash instruction using factory image:

1. Connect the computer to the LAN port of BHR-4GRV2
2. Connect power cable to BHR-4GRV2 and turn on it
3. Access to "http://192.168.12.1/" and open firmware update
page ("ファームウェア更新")
4. Select the OpenWrt factory image and click update ("更新実行")
button
5. Wait ~120 seconds to complete flashing

Signed-off-by: INAGAKI Hiroshi <musashino.open@gmail.com>

target/linux/ath79/image/Makefile

@@ -75,6 +75,7 @@ ifeq ($(SUBTARGET),nand)
 include ./nand.mk
 endif
 ifeq ($(SUBTARGET),tiny)
+include ./tiny.mk
 include ./tiny-netgear.mk
 include ./tiny-tp-link.mk
 endif

target/linux/ath79/image/tiny.mk

@@ -0,0 +1,18 @@
+DEVICE_VARS += ROOTFS_SIZE
+
+define Device/buffalo_bhr-4grv2
+  ATH_SOC := qca9558
+  DEVICE_TITLE := Buffalo BHR-4GRV2
+  BOARDNAME := BHR-4GRV2
+  ROOTFS_SIZE := 14528k
+  KERNEL_SIZE := 1472k
+  IMAGE_SIZE := 16000k
+  IMAGES += factory.bin
+  IMAGE/sysupgrade.bin := \
+    append-rootfs | pad-rootfs | pad-to $$$$(ROOTFS_SIZE) | \
+    append-kernel | append-metadata | check-size $$$$(IMAGE_SIZE)
+  IMAGE/factory.bin := append-kernel | \
+    pad-to $$$$(KERNEL_SIZE) | append-rootfs | pad-rootfs | mkbuffaloimg
+  SUPPORTED_DEVICES += bhr-4grv2
+endef
+TARGET_DEVICES += buffalo_bhr-4grv2