Fixed typo

Signed-off-by: Daan Hoogland <daan@onecht.net>
Fix for Coverity issues CID_1116744, CID_1116718 and CID_1116682, all related to resource leak

Signed-off-by: Daan Hoogland <daan@onecht.net>
CLOUDSTACK-5293: fix issue when collect vm disk statistics from iso