scripts: kwboot: add support for Marvell Dove ...

Marvell Dove SoC also has an UART bootmode to upload payload after
powerup. In contrast to Kirkwood and Armada 370/XP, Dove does not
respond to a special sequence sent on UART0 but requires to be
booted into UART bootmode by bootstraps. This is usually done by
pressing a push button that will set bootstraps accordingly.

This patch adds a new option, documentation and corresponding prompts
to support the above requirements. Also a left-over option ('-p')
is removed.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

scripts: add kwboot tool ...

This tool is used with Marvell EBU SoC to trigger the UART boot mode
provided by the SoC BootROM, and push the bootloader image to the
target using the Xmodem protocol.

It has been taken from the U-Boot source code, with minor
modifications to make it work with Armada 370/XP platforms.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>