config: Fix a docker initialization bug.
config: Fix a docker initialization bug.

If docker.service got unlucky and some other service created /opt
first, it would fail to boot.  This patch fixes the problem by using
-p.

NetSys/quilt,mmussomele/quilt,stevenlin598/quilt,quilt/quilt,stevenlin598/quilt,quilt/quilt,ejj/quilt-dev,kelda/kelda,NetSys/quilt,LuiseV/quilt,quilt/quilt,secant/quilt,kelda/kelda,kayousterhout/quilt,mmussomele/quilt,kklin/quilt,kklin/quilt,kayousterhout/quilt,secant/quilt,kayousterhout/quilt,ZhongtianWang/quilt,ZhongtianWang/quilt,akshayknarayan/quilt,PenguinToast/quilt,tejasmanohar/quilt,LuiseV/quilt,PenguinToast/quilt,PenguinToast/quilt,LuiseV/quilt,kelda/kelda,LuiseV/quilt,mmussomele/quilt,tejasmanohar/quilt,NetSys/quilt,ejj/quilt-dev,tejasmanohar/quilt,mmussomele/quilt,secant/quilt,akshayknarayan/quilt,akshayknarayan/quilt,akshayknarayan/quilt,kklin/quilt,kklin/kelda,ZhongtianWang/quilt,ejj/quilt-dev,quilt/quilt,kklin/quilt,ZhongtianWang/quilt,LuiseV/quilt,secant/quilt,kklin/kelda,kayousterhout/quilt,PenguinToast/quilt,stevenlin598/quilt,NetSys/quilt,stevenlin598/quilt,stevenlin598/quilt,tejasmanohar/quilt,stevenlin598/quilt,kklin/kelda,mmussomele/quilt,PenguinToast/quilt,mmussomele/quilt,ejj/quilt-dev,kklin/kelda,secant/quilt,kelda/kelda,NetSys/quilt