dt-bindings: arm: Add devicetree binding for Thor96 Board

Add devicetree binding for Thor96 Board from Einfochips. This board is
one of the 96Boards Consumer Edition platform powered by NXP i.MX8MQ SoC.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>