board/friendlyarm/nanopi-neo2/genimage.cfg: fix comment
For consistency comment '# 1MB - 40K' must be '# 1MB - 40KB'.
Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>