arm64: dts: rockchip: Add rk3588 Edgeble Neu6 Model B SoM

Neural Compute Module 6B(Neu6B) is a 96boards SoM-CB compute module
based on Rockchip RK3588J from Edgeble AI.

General features:
- Rockchip RK3588J
- up to 32GB LPDDR4x
- up to 128GB eMMC
- 2x MIPI CSI2 FPC

On module WiFi6/BT5 is available in the following Neu6 variants.

Neu6B needs to mount on top of associated Edgeble Neu6B IO boards for
creating complete platform solutions.

Enable eMMC for now to boot Linux successfully.

Add support for Edgeble Neu6 Model B SoM.
Signed-off-by: Jagan Teki <jagan@edgeble.ai>
Link: https://lore.kernel.org/r/20230516163454.997736-3-jagan@edgeble.aiSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3588-edgeble-neu6b.dtsi

+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright (c) 2023 Edgeble AI Technologies Pvt. Ltd.
+ */
+
+/ {
+	compatible = "edgeble,neural-compute-module-6b", "rockchip,rk3588";
+
+	aliases {
+		mmc0 = &sdhci;
+	};
+
+	vcc12v_dcin: vcc12v-dcin-regulator {
+		compatible = "regulator-fixed";
+		regulator-name = "vcc12v_dcin";
+		regulator-always-on;
+		regulator-boot-on;
+		regulator-min-microvolt = <12000000>;
+		regulator-max-microvolt = <12000000>;
+	};
+};
+
+&sdhci {
+	bus-width = <8>;
+	no-sdio;
+	no-sd;
+	non-removable;
+	max-frequency = <200000000>;
+	mmc-hs400-1_8v;
+	mmc-hs400-enhanced-strobe;
+	status = "okay";
+};