arm: bcmbca: add bcm6813 SoC support

BCM6813 is a Broadcom B53 based PON and WLAN AP router SoC. It is part
of the BCA (Broadband Carrier Access origin) chipset family so it's
added under ARCH_BCMBCA platform. This initial support includes a
bare-bone implementation and dts with CPU subsystem, memory and ARM
PL011 uart.

This SoC is supported in the linux-next git repository so the dts and
dtsi files are copied from linux.

The u-boot image can be loaded from flash or network to the entry point
address in the memory and boot from there to the console.

Signed-off-by: William Zhang <william.zhang@broadcom.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
diff --git a/arch/arm/dts/bcm96813.dts b/arch/arm/dts/bcm96813.dts
new file mode 100644
index 0000000..af17091
--- /dev/null
+++ b/arch/arm/dts/bcm96813.dts
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright 2022 Broadcom Ltd.
+ */
+
+/dts-v1/;
+
+#include "bcm6813.dtsi"
+
+/ {
+	model = "Broadcom BCM96813 Reference Board";
+	compatible = "brcm,bcm96813", "brcm,bcm6813", "brcm,bcmbca";
+
+	aliases {
+		serial0 = &uart0;
+	};
+
+	chosen {
+		stdout-path = "serial0:115200n8";
+	};
+
+	memory@0 {
+		device_type = "memory";
+		reg = <0x0 0x0 0x0 0x08000000>;
+	};
+};
+
+&uart0 {
+	status = "okay";
+};