bcm968360bg: add initial support

This add the initial support of the broadcom reference
board bcm968360bg with a bcm68360 SoC.

This board has 512 MB of RAM, 256 MB of flash (nand),
2 USB port, 1 UART, and 4 ethernet ports.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>

include/configs/broadcom_bcm968360bg.h

@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2020 Philippe Reynes <philippe.reynes@softathome.com>
+ */
+
+#include <linux/sizes.h>
+
+/*
+ * common
+ */
+
+/* UART */
+#define CONFIG_SYS_BAUDRATE_TABLE	{ 9600, 19200, 38400, 57600, 115200, \
+					  230400, 500000, 1500000 }
+/* Memory usage */
+#define CONFIG_SYS_MAXARGS		24
+#define CONFIG_SYS_MALLOC_LEN		(1024 * 1024)
+
+/*
+ * 6858
+ */
+
+/* RAM */
+#define CONFIG_SYS_SDRAM_BASE		0x00000000
+
+/* U-Boot */
+#define CONFIG_SYS_INIT_SP_ADDR		(CONFIG_SYS_TEXT_BASE + SZ_16M)
+#define CONFIG_SYS_LOAD_ADDR		CONFIG_SYS_TEXT_BASE
+
+#define CONFIG_SKIP_LOWLEVEL_INIT
+
+#ifdef CONFIG_MTD_RAW_NAND
+#define CONFIG_SYS_MAX_NAND_DEVICE	1
+#define CONFIG_SYS_NAND_SELF_INIT
+#define CONFIG_SYS_NAND_ONFI_DETECTION
+#endif /* CONFIG_MTD_RAW_NAND */
+
+/*
+ * 968360bg
+ */