Use right service name when stopping tgt in unstack.sh

On non-deb systems, 'tgt' is 'tgtd'.

Change-Id: I357b47cf117a5e615eb4af9603b7c5670e5cff1c
diff --git a/unstack.sh b/unstack.sh
index 6a55a0a..64de915 100755
--- a/unstack.sh
+++ b/unstack.sh
@@ -54,7 +54,12 @@
         echo "iSCSI target cleanup needed:"
         echo "$TARGETS"
     fi
-    stop_service tgt
+
+    if [[ "$os_PACKAGE" = "deb" ]]; then
+        stop_service tgt
+    else
+        stop_service tgtd
+    fi
 fi
 
 if [[ -n "$UNSTACK_ALL" ]]; then