display: Fix making a tiled monitor primary again

Don't break out of loop if we weren't primary, as this
is stopping the user swapping back and forward between
primary and secondary with a tiled monitor.

i.e. user sets monitor to secondary and attempts to
go back to primary and it fails to move it.

https://bugzilla.gnome.org/show_bug.cgi?id=751680

panels/display/cc-display-panel.c

@@ -2312,8 +2312,6 @@ show_setup_dialog (CcDisplayPanel *panel)
                    * output is no longer primary */
 
                   gnome_rr_output_info_set_primary (outputs[i], !primary);
-                  if (!was_primary)
-                    break;
                 }
             }