Fixes /dev volume, missed in the previous commit [1].
iscsid was installing the devices in /dev but zun-compute
could not see them due to the emulated /dev volume.
[1] I2c4aa666ff9f952e32c450347d31ddbf2e58209e
Change-Id: Ic72c910b92765b9a6f59224728e9c4ea2482bc5a
Related-bug: #1797448
Related-bug: #1848933