board: rockchip: add Rockchip Toybrick TB-RK3588X board

TB-RK3588X board is a Rockchip Toybrick RK3588 based development board.

Specification:
	Rockchip Rk3588 SoC
	4x ARM Cortex-A76, 4x ARM Cortex-A55
	8/16GB Memory LPDDR4x
	Mali G610MC4 GPU
	2× MIPI-CSI0 Connector
	1x 2Lanes PCIe3.0 Connector
	1x SATA3.0 Connector
	32GB eMMC Module
	2x USB 2.0, 2x USB 3.0
	1x HDMI Output, 1x HDMI Input
	2x Ethernet Port

Functions work normally:
	[1] USB2.0 Host
	[2] Ethernet0 with PHY RTL8211F

More information can be obtained from the following websites:
	[1] https://t.rock-chips.com/en/wiki/EN/tb-rk3588x_en/index.html
	[2] http://t.rock-chips.com/

Kernel commits:
	8ffe365f8dc7 ("arm64: dts: rockchip: Add devicetree support for TB-RK3588X board")
	7140387ff49d ("dt-bindings: arm: rockchip: Add Toybrick TB-RK3588X")

Reviewed-by: Weizhao Ouyang <weizhao.ouyang@arm.com>
Signed-off-by: Elon Zhang <zhangzj@rock-chips.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/doc/board/rockchip/rockchip.rst b/doc/board/rockchip/rockchip.rst
index bfe7aed..c35f256 100644
--- a/doc/board/rockchip/rockchip.rst
+++ b/doc/board/rockchip/rockchip.rst
@@ -125,6 +125,7 @@
      - Turing Machines RK1 (turing-rk1-rk3588)
      - Radxa ROCK 5A (rock5a-rk3588s)
      - Radxa ROCK 5B (rock5b-rk3588)
+     - Rockchip Toybrick TB-RK3588X (toybrick-rk3588)
      - Theobroma Systems RK3588-SBC Jaguar (jaguar-rk3588)
      - Xunlong Orange Pi 5 (orangepi-5-rk3588s)
      - Xunlong Orange Pi 5 Plus (orangepi-5-plus-rk3588)