mk_fs: force tunefs prompting

Newer tune2fs will throw up a 5 second prompt when running:
Setting UUID on a checksummed filesystem could take some time.
Proceed anyway (or wait 5 seconds) ? (y,n)

Redirect stdin so it doesn't prompt us.

BUG=None
TEST=`./build_image` tune2fs prompt no longer waits 5 seconds

Change-Id: Ie8a4a1db0177a6ad838b9b450b432fc56e55c9c8
Reviewed-on: https://chromium-review.googlesource.com/461962
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
1 file changed