ARM: dts: imx: add ZII RDU1 board

This adds support for the Zodiac Inflight Innovations RDU1 board,
which is based on the i.MX51.

It is the predecessor of the already supported ZII RDU2 board and
relies on the bootloader in the same way to enable correct display
and touchscreen nodes.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Tested-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>