tools: kwboot: Set debug flag to 1

This should enable BootROM output on UART.

(At least on A385 BootROM this is broken, BootROM ignores this debug
 flag and does not enable its output on UART if some valid image is
 available in SPI-NOR.)

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