The Toradex board Iris V2 has an LVDS transceiver which is
configured with 4 signals. Add corresponding pins into the
separate pingroup to be able to manage the transceiver.
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>