boot: looks like we can use about 200Mb

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>

05_generate_boot.sh

@@ -13,7 +13,7 @@ cp -v ./bins/light_c906_audio.bin ./ignore/.boot
 cp -v ./deploy/Image ./ignore/.boot
 cp -v ./deploy/light-beagle.dtb ./ignore/.boot
 
-dd if=/dev/zero of=./deploy/boot.ext4 count=10000 bs=4096
+dd if=/dev/zero of=./deploy/boot.ext4 bs=1 count=0 seek=100M
 mkfs.ext4 -F ./deploy/boot.ext4 -d ./ignore/.boot
 
 if [ -f ./.05_generate_boot.sh ] ; then