tools: kwboot: Properly finish xmodem transfer

After kwboot sends EOT, BootROM sends back ACK. Add code for handling
this and retry sending EOT on error.

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>
1 file changed