[uboot] create uboot from github:

repo: https://github.com/u-boot/u-boot
	commit: d80bb749fab53da72c4a0e09b8c2d2aaa3103c91

Change-Id: Ie6434426e1ec15bc08bb1832798e371f3fd5fb29

u-boot-2021.10/arch/mips/lib/stack.c

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <common.h>
+#include <init.h>
+#include <log.h>
+#include <asm/global_data.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+int arch_reserve_stacks(void)
+{
+	/* reserve space for exception vector table */
+	gd->start_addr_sp -= 0x500;
+	gd->start_addr_sp &= ~0xFFF;
+	gd->irq_sp = gd->start_addr_sp;
+	debug("Reserving %d Bytes for exception vector at: %08lx\n",
+	      0x500, gd->start_addr_sp);
+
+	return 0;
+}