make_chroot: drop unused --useimage flag

cros_sdk doesn't use it, and no other code uses this script, so drop it.

BUG=b:191307774
TEST=`cros_sdk` still works

Change-Id: Ib7ad5a19c7db0536f6e6a9c66a63fccc6a077783
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/2971573
Reviewed-by: Alex Klein <saklein@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
1 file changed