bandwidth-usage.tree: Changed $PREVIOUS_TRAFFIC exit value from 1 to 0

Changed to continue the generation of the XML file, even when there's no
bandwidth usage collected data.

Signed-off-by: Erik Alexandre Pucci <eap08@c3sl.ufpr.br>
Signed-off-by: Josiney de Souza <josineys@c3sl.ufpr.br>

scripts/collect/use/bandwidth-usage.tree

@@ -162,8 +162,8 @@ fi
 
 PREVIOUS_TRAFFIC="${PREFIX}/../../../net/previous-traffic.txt"
 
-test -f "${PREVIOUS_TRAFFIC}" || exit 1
-test -s $PREVIOUS_TRAFFIC || exit 1
+test -f "${PREVIOUS_TRAFFIC}" || exit 0
+test -s $PREVIOUS_TRAFFIC || exit 0
 
 # Call the function xml_data_generator to generate the data to XML
 xml_data_generator