dt-bindings: arm: fsl: Add Engicam i.Core MX8M Mini EDIMM2.2 Starter Kit

i.Core MX8M Mini is an EDIMM SoM based on NXP i.MX8M Mini from Engicam.

EDIMM2.2 Starter Kit is an EDIMM 2.2 Form Factor Capacitive Evaluation
Board from Engicam.

i.Core MX8M Mini needs to mount on top of this Evaluation board for
creating complete i.Core MX8M Mini EDIMM2.2 Starter Kit.

Add bindings for it.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>