Fix nova-volume-usage-audit
Fix nova-volume-usage-audit

utils.default_cfgfile have been removed from nova/utils, so
remove it here as well.

Fixes LP: #1065069

Change-Id: I71f6c7850123ef0c1ef4fedf608de13b31dafb32
Signed-off-by: Chuck Short <753a8074f04ffd62a8fff7516e3ae689be8e35ad@canonical.com>

n0ano/gantt,n0ano/gantt