USS: initialize a list before using it.

Change-Id: Iba35e4397646a67384e878fbe7bdfb7586fc07f9
BUG: 1130888
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
Reviewed-on: http://review.gluster.org/8569
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>