malta: add script & instructions to flash U-boot

This patch adds a script which may be used with MIPS Navigator Console
and a MIPS Nagivator Probe in order to flash U-boot to a MIPS Malta
development board.

Please see the newly added doc/README.malta for usage instructions.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>

board/imgtec/malta/flash-malta-boot.tcl

+#
+# Copyright (C) 2013 Imagination Technologies
+#
+# Programs a MIPS Malta boot flash with a flat binary image.
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+proc flash-boot { binfile } {
+  puts "flash monitor binary $binfile"
+  config Coherent on
+  config CoherencyDuringLoad on
+
+  if {[endian]=="big"} {
+    puts "CPU in BE mode"
+    flash device sharp_16x32_be;
+  } else {
+    puts "CPU in LE mode"
+    flash device sharp_16x32;
+  }
+
+  flash clear all;
+  flash set 0xBE000000..0xBE0FFFFF
+  flash erase sector 0xbe000000;
+  flash erase sector 0xbe020000;
+  flash erase sector 0xbe040000;
+  flash erase sector 0xbe060000;
+  flash erase sector 0xbe080000;
+  flash erase sector 0xbe0a0000;
+  flash erase sector 0xbe0c0000;
+  flash erase sector 0xbe0e0000;
+  puts "finished erasing boot flash";
+
+  puts "programming flash, please be patient"
+  load bin 0xbe000000 $binfile size4
+
+  flash clear all
+  config CoherencyDuringLoad off
+  puts "finished programming boot flash";
+}

doc/README.malta

+MIPS Malta board
+
+How to flash using a MIPS Navigator Probe:
+
+  - Ensure that your Malta has jumper JP1 fitted. Without this jumper you will
+    be unable to flash your Malta using a Navigator Probe.
+
+  - Connect Navigator Console to your probe and Malta as usual.
+
+  - Within Navigator Console run the following commands:
+
+      source /path/to/u-boot/board/malta/flash-malta-boot.tcl
+      reset
+      flash-boot /path/to/u-boot/u-boot.bin
+
+  - You should now be able to reboot your Malta to a U-boot shell.