ath79: add support for MikroTik RouterBOARD 922UAGS-5HPacD

This patch ports support for the MikroTik RouterBOARD 922UAGS-5HPacD
with a built-in 802.11ac High-Power radio (31dBm), which was already
available in the ar71xx target.

See https://mikrotik.com/product/RB922UAGS-5HPacD for more info.

Specifications:
- SoC: Qualcomm Atheros QCA9558 (720 MHz)
- RAM: 128 MB
- Storage: 128 MB NAND
- Wireless: external QCA9882 802.11a/ac 2x2:2
- Ethernet: 1x 1000/100/10 Mbps, integrated, via AR8031 PHY, passive PoE-in 24V
- SFP: 1x host
- USB: 1x 2.0 type A
- PCIe: 1x Mini slot (also contains USB 2.0 for 3G/LTE modems)
- SIM slot: 1x mini-SIM

Working:
- Board/system detection
- SPI and NAND storage
- PCIe
- USB type A host
- Wireless
- Ethernet
- LEDs (user, phy0)
- Reset button
- Sysupgrade to/from ar71xx

Not supported:
- RSSI LEDs
- SFP cage

Installation methods:
- Sysupgrade from ar71xx (it is advisable to use the -n option to
wipe any previous settings), or
- Boot the initramfs image via TFTP and then flash the sysupgrade
image using "sysupgrade -n"

Signed-off-by: Roger Pueyo Centelles <roger.pueyo@guifi.net>

target/linux/ath79/image/nand.mk

@@ -1,3 +1,4 @@
+include ./common-mikrotik.mk
 include ./common-netgear.mk	# for netgear-uImage
 
 # attention: only zlib compression is allowed for the boot fs
@@ -110,6 +111,19 @@ define Device/glinet_gl-ar750s-nor
 endef
 TARGET_DEVICES += glinet_gl-ar750s-nor
 
+define Device/mikrotik_routerboard-922uags-5hpacd
+  $(Device/mikrotik)
+  SOC := qca9558
+  DEVICE_MODEL := RouterBOARD 922UAGS-5HPacD
+  BOARD_NAME := routerboard
+  IMAGE/sysupgrade.bin = append-kernel | kernel2minor -s 2048 -e -c | \
+	sysupgrade-tar kernel=$$$$@ | append-metadata
+  DEVICE_PACKAGES += kmod-ath10k-ct ath10k-firmware-qca988x-ct \
+	kmod-usb2 nand-utils
+  SUPPORTED_DEVICES += rb-922uags-5hpacd
+endef
+TARGET_DEVICES += mikrotik_routerboard-922uags-5hpacd
+
 # fake rootfs is mandatory, pad-offset 129 equals (2 * uimage_header + 0xff)
 define Device/netgear_ath79_nand
   DEVICE_VENDOR := NETGEAR