rockchip: add support for Radxa ROCK 3B

Radxa ROCK 3B is a Pico-ITX form factor SBC[1] using the Rockchip
RK3568(J).

Hardware
--------
- Rockchip RK3568(J) SoC
- Quad A55 CPU
- Mali-G52 GPU
- 1 TOPS @ INT8 NPU
- 2GB/4GB/8GB LPDDR4 RAM
- eMMC connector
- Micro SD Card slot
- NVMe SSD through the M.2 M Key (2-lane PCIe 3.0)
- SPI Flash for bootloader
- 2x Gigabit ethernet port (one supports PoE with add-on PoE HAT)
- 1x M.2 E Key socket with SDIO, UART and USB interfaces
- 1x M.2 B Key socket with PCIe, SATA, and USB interfaces
- 1x SIM card socket
- 1x USB 3.0 Type-A HOST port
- 1x USB 3.0 Type-A OTG port
- 2x USB 2.0 Type-A HOST ports
- 40 Pin GPIO header

[1] https://radxa.com/products/rock3/3b

Installation
------------
Uncompress the OpenWrt sysupgrade and write it to a micro SD card or
internal eMMC using dd.

Signed-off-by: FUKAUMI Naoki <[email protected]>
Link: openwrt#16185
Signed-off-by: Hauke Mehrtens <[email protected]>

package/boot/uboot-rockchip/Makefile

@@ -228,6 +228,13 @@ define U-Boot/rock-3a-rk3568
     radxa_rock-3a
 endef
 
+define U-Boot/rock-3b-rk3568
+  $(U-Boot/rk3568/Default)
+  NAME:=ROCK 3B
+  BUILD_DEVICES:= \
+    radxa_rock-3b
+endef
+
 
 # RK3588 boards
 
@@ -292,6 +299,7 @@ UBOOT_TARGETS := \
   nanopi-r5s-rk3568 \
   radxa-e25-rk3568 \
   rock-3a-rk3568 \
+  rock-3b-rk3568 \
   rock5b-rk3588 \
   nanopc-t6-rk3588 \
   nanopi-r6s-rk3588s \