rockchip: rk3568: Add EmbedFire Lubancat 2 support

LubanCat2 is a rk3568 based SBC from EmbedFire.

Specification:
- Rockchip rk3568
- LPDDR4/4X 1/2/4/8 GB
- TF scard slot
- eMMC 8/32/64/128 GB
- Gigabit ethernet x 2
- HDMI out
- USB 2.0 Host x 1
- USB 2.0 Type-C OTG x 1
- USB 3.0 Host x 1
- Mini PCIE interface for WIFI/BT module
- M.2 key for 2280 NVME
- 40 pin header

The dts file is sync from linux mainline.

Signed-off-by: Andy Yan <andyshrk@163.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/dts/rk3568-lubancat-2-u-boot.dtsi b/arch/arm/dts/rk3568-lubancat-2-u-boot.dtsi
new file mode 100644
index 0000000..27c6277
--- /dev/null
+++ b/arch/arm/dts/rk3568-lubancat-2-u-boot.dtsi
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2023 Rockchip Electronics Co., Ltd
+ * (C) Copyright 2023 Andy Yan <andyshrk@163.com>
+ */
+
+#include "rk356x-u-boot.dtsi"
+
+/ {
+	chosen {
+		stdout-path = &uart2;
+	};
+};
+
+&sdhci {
+	cap-mmc-highspeed;
+	mmc-ddr-1_8v;
+	mmc-hs400-1_8v;
+	mmc-hs400-enhanced-strobe;
+	pinctrl-0 = <&emmc_bus8 &emmc_clk &emmc_cmd &emmc_datastrobe>;
+};
+
+&uart2 {
+	bootph-all;
+	clock-frequency = <24000000>;
+	status = "okay";
+};