dt-bindings: arm: fsl: add SKOV imx6q and imx6dl based boards

Add SKOV imx6q/dl LT2, LT6 and mi1010ait-1cp1 boards.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>