Shrink rootfs after y2020 game

We aren't running python code anymore.  This shrinks flashing time
significantly.

Change-Id: I54aa7f90c05383c487deff0bd8c2f465f2ef0c55
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/y2020/vision/rootfs/modify_rootfs.sh b/y2020/vision/rootfs/modify_rootfs.sh
index f08e635..ae1e493 100755
--- a/y2020/vision/rootfs/modify_rootfs.sh
+++ b/y2020/vision/rootfs/modify_rootfs.sh
@@ -44,7 +44,7 @@
 else
   OFFSET="$(/sbin/fdisk -lu "${IMAGE}" | grep "${IMAGE}2" | awk '{print 512*$2}')"
 
-  if [[ "$(stat -c %s "${IMAGE}")" < 3000000000 ]]; then
+  if [[ "$(stat -c %s "${IMAGE}")" < 2000000000 ]]; then
     echo "Growing image"
     dd if=/dev/zero bs=1G count=1 >> "${IMAGE}"
     START="$(/sbin/fdisk -lu "${IMAGE}" | grep "${IMAGE}2" | awk '{print $2}')"