dt-bindings: arm: fsl: add verdin imx8mm mallow board

dt-bindings: arm: fsl: add verdin imx8mm mallow board

Add Mallow carrier board for wifi and nonwifi variants of Toradex Verdin
IMX8MM SoM. Mallow is a low-cost carrier board in the Verdin family with
a small form factor and build for volume production making it ideal for
industrial and embedded applications.

https://www.toradex.com/products/carrier-board/mallow-carrier-board

Signed-off-by: Joao Paulo Goncalves <joao.goncalves@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>