tools: kwboot: Inject baudrate change back code after data part

tools: kwboot: Inject baudrate change back code after data part

Some vendor U-Boot kwbimage binaries (e.g. those for A375) have load
address set to zero. Therefore it is not possible to inject code which
changes baudrate back to 115200 Bd before the data part.

So instead inject it after the data part and change kwbimage execution
address to that offset. Also store original execution address into
baudrate change code, so after it changes baudrate back to 115200 Bd, it
can jump to orignal address.

Signed-off-by: Pali Rohár <pali@kernel.org>
[ refactored ]
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>