Update the board cmake to use xsdb runner, If users would like to
use default xsdb.cfg then need to pass the fsbl.elf binary via
--fsbl option when using west flash or twister commands.
Usage:
1) west flash --runner xsdb --elf-file kv260_r5/zephyr/zephyr.elf
--fsbl <path>/fsbl.elf
2) ./scripts/twister -p kv260_r5 --west-runner xsdb --device-testing
--device-serial /dev/ttyUSB0 --west-flash="--fsbl=<path>/fsbl.elf"
Signed-off-by: Appana Durga Kedareswara rao <appana.durga.kedareswara.rao@amd.com>