Use correct spelling of "U-Boot"

Correct spelling of "U-Boot" shall be used in all written text
(documentation, comments in source files etc.).

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Minkyu Kang <mk7.kang@samsung.com>

malta: correct tcl script path in README.malta

README.malta referred to board/malta, but malta has now been moved
within board/imgtec/, so correct the path.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Cc: Paul Burton <paul.burton@imgtec.com>

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>