ceph-volume: process: disable stdin param of run()

ceph-volume: process: disable stdin param of run()

we cannot use process.communicate() to feed the Popen with input,
because, upon return of process.communicate() the stdout,stderr are
closed. see https://docs.python.org/2/library/subprocess.html#subprocess.Popen.communicate .

Signed-off-by: Kefu Chai <kchai@redhat.com>