reference Sonar CLI from the correct directory

Change-Id: Ic356be2bc41ebc04227de613a9860473ecbc121f
diff --git a/jjb/onos/onos-sonar.sh b/jjb/onos/onos-sonar.sh
index 04b1a8c..db2b298 100644
--- a/jjb/onos/onos-sonar.sh
+++ b/jjb/onos/onos-sonar.sh
@@ -2,9 +2,11 @@
 ONOS_ROOT=`pwd`
 . tools/build/envDefaults
 
-curl -L -o /tmp/sonar-scanner-cli.zip -X GET https://sonarsource.bintray.com/Distribution/sonar-scanner-cli/sonar-scanner-cli-3.0.3.778.zip
+SONAR_SCANNER=sonar-scanner-3.0.3.778
+
+curl -L -o /tmp/sonar-scanner-cli.zip -X GET https://sonarsource.bintray.com/Distribution/sonar-scanner-cli/$SONAR_SCANNER.zip
 unzip /tmp/sonar-scanner-cli.zip
 
-sonar/bin/sonar-scanner
+$SONAR_SCANNER/bin/sonar-scanner