Use baremetal-interface-add, not baremetal-add-interface

Since nova doesn't have such subcommand.

Change-Id: I3c99de38f959418f82d45078c7784ba6ab60c383
diff --git a/lib/baremetal b/lib/baremetal
index 24cce9f..17a967f 100644
--- a/lib/baremetal
+++ b/lib/baremetal
@@ -427,7 +427,7 @@
        "$mac_1" \
        | grep ' id ' | get_field 2 )
     [ $? -eq 0 ] || [ "$id" ] || die "Error adding baremetal node"
-    id2=$(nova baremetal-add-interface "$id" "$mac_2" )
+    id2=$(nova baremetal-interface-add "$id" "$mac_2" )
     [ $? -eq 0 ] || [ "$id2" ] || die "Error adding interface to barmetal node $id"
 }