update_kernel: automatically fallback to remote bootargs

If build_image hasn't been run, today we fail by default.  However, we
can automatically fallback to using the remote bootargs as that's what
most people want anyways.

TEST=`./update_kernel.sh --remote=` works after deleting build/images/

Change-Id: I2a8861025c8592a04d93bb38a98748e0fa7350b5
Reviewed-on: https://chromium-review.googlesource.com/473947
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
1 file changed