arm: add support for Hisilicon HiSTB family SoCs

First supported chip is hi3798mv200 (which is similar to Hi3798cv200
used by poplar).

Signed-off-by: Yang Xiwen <forbidden405@outlook.com>
diff --git a/arch/arm/mach-histb/board_common.c b/arch/arm/mach-histb/board_common.c
new file mode 100644
index 0000000..a26c206
--- /dev/null
+++ b/arch/arm/mach-histb/board_common.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Board init file for all histb boards
+ *
+ * (C) Copyright 2023 Yang Xiwen <forbidden405@outlook.com>
+ */
+
+#include <common.h>
+#include <fdtdec.h>
+#include <init.h>
+#include <asm/system.h>
+
+int __weak board_init(void)
+{
+	return 0;
+}
+
+int __weak dram_init_banksize(void)
+{
+	return fdtdec_setup_memory_banksize();
+}
+
+int __weak dram_init(void)
+{
+	return fdtdec_setup_mem_size_base();
+}
+
+void __weak reset_cpu(void)
+{
+	psci_system_reset();
+}