tools: kwboot: Increase blk_rsp_timeo to 2s

Fix xmodem retry mechanism if some bytes from xmodem packet were lost and
BootROM is still waiting for completing previous xmodem packet.

It is required to wait at least 1.312s on A385, otherwise BootROM does not
accept next xmodem packet if previous one was not completely transferred.

2s should be enough timeout cause that BootROM will drop incomplete xmodem
packet and expects new packet.

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