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: Paul Burton <paul.burton@imgtec.com>
diff --git a/doc/README.malta b/doc/README.malta
new file mode 100644
index 0000000..a495d02
--- /dev/null
+++ b/doc/README.malta
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+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.