Some minor improvements are made in this patchset:
1) Move osd_disk_prechecks to the very beginning to make sure the
required variables are set before running the bulk of the script.
2) Specify variables in a more consistent manner for readability.
3) Remove variables from CLI commands that are not used/set.
Change-Id: I6167b277e111ed59ccf4415e7f7d178fe4338cbd
b3ebb46ce2