Fixed profile to work with new prerequisites.xml

Change-Id: I3578237480330a12e50d3375cfd0157cdb150628
diff --git a/tools/dev/bash_profile b/tools/dev/bash_profile
index f39c2ce..9a8ccbf 100644
--- a/tools/dev/bash_profile
+++ b/tools/dev/bash_profile
@@ -112,6 +112,7 @@
         unset ONOS_CELL ONOS_NIC ONOS_IP ONOS_APPS ONOS_BOOT_FEATURES
         unset OCI OCN OCT ONOS_INSTANCES ONOS_USER ONOS_GROUP ONOS_FEATURES
         unset $(env | sed -n 's:\(^OC[0-9]\{1,\}\)=.*:\1 :g p')
+        export ONOS_USER=${ONOS_USER:-sdn}
         export ONOS_WEB_USER=onos
         export ONOS_WEB_PASS=rocks
         export ONOS_CELL=$1