arm64: dts: qcom: Add OnePlus Nord N100 (billie2)

This adds the initial device tree support for OnePlus Nord N100
(codename billie2) phone. It is based on SM4250 SoC. Currently it boots
and runs initrd init, displaying dmesg over the screen. It also support
ramoops for debugging.
Signed-off-by: Iskren Chernev <iskren.chernev@gmail.com>

arch/arm64/boot/dts/qcom/sm4250-oneplus-billie2.dts

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2021, Iskren Chernev <iskren.chernev@gmail.com>
+ */
+
+/dts-v1/;
+
+#include "sm4250.dtsi"
+
+/ {
+	model = "OnePlus Nord N100";
+	compatible = "oneplus,billie2", "qcom,sm4250";
+
+	/* required for bootloader to select correct board */
+	qcom,msm-id = <0x1a1 0x10000 0x1bc 0x10000>;
+	qcom,board-id = <0x1000b 0x00>;
+
+	aliases {
+	};
+
+	chosen {
+		bootargs = "earlycon=tty0 console=tty0";
+
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		stdout-path = "framebuffer0";
+
+		framebuffer0: framebuffer@9d400000 {
+			compatible = "simple-framebuffer";
+			reg = <0 0x5c000000 0 (1600 * 720 * 4)>;
+			width = <720>;
+			height = <1600>;
+			stride = <(720 * 4)>;
+			format = "a8r8g8b8";
+			status= "okay";
+		};
+	};
+
+	reserved-memory {
+		mtp_mem: memory@cc300000 {
+			reg = <0x00 0xcc300000 0x00 0xb00000>;
+			no-map;
+		};
+
+		param_mem: memory@cc200000 {
+			reg = <0x00 0xcc200000 0x00 0x100000>;
+			no-map;
+		};
+
+		bootloader_log_mem: memory@5fff7000 {
+			reg = <0x00 0x5fff7000 0x00 0x8000>;
+			no-map;
+		};
+
+		ramoops@cbe00000 {
+			compatible = "ramoops";
+			reg = <0x0 0xcbe00000 0x0 0x400000>;
+			record-size = <0x40000>;
+			pmsg-size = <0x200000>;
+			console-size = <0x40000>;
+			ftrace-size = <0x40000>;
+		};
+	};
+};