dt-bindings: arm: fsl: Add Y Soft IOTA Crux/Crux+ boards

Add devicetree binding for Crux/Crux+ boards from the IOTA family.
These boards have the very same HW configuration as the Orion board
except the usage of Quad/QuadPlus SoC.

Signed-off-by: Michal Vokáč <michal.vokac@ysoft.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>