findbugs: Random object recreated each call

for better random use the same object instead of creating a new one.

findbugs reason:
DMI: Random object created and used only once (DMI_RANDOM_USED_ONLY_ONCE)

Change-Id: I4d88d7c80698e6d0ec1fed9ba8cb78c2b524ebae
Signed-off-by: Shahar Havivi <shavivi@redhat.com>