arm64: dts: imx8mp-msc-sm2s: Add device trees for MSC SM2S-IMX8PLUS SoM and carrier board

Add device trees for one of a number of MSC's (parent company, Avnet)
variants of the SM2S-IMX8PLUS system on module along with the compatible
SM2S-SK-AL-EP1 carrier board. As the name suggests, this family of SoMs use
the NXP i.MX8MP SoC and provide the SMARC module interface.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>