dt-bindings: arm: add imx8mp-libra-rdk-fpsc

dt-bindings: arm: add imx8mp-libra-rdk-fpsc

imx8mp-libra-rdk-fpsc is a development board based on the phyCORE-i.MX
8M Plus FPSC SoM. Add its description and binding. The
imx8mp-phycore-fpsc som differs from the existing phyCORE-i.MX 8M Plus
(dts: imx8mp-phycore-som.dtsi) in its physical form regarding the ball
grid array. Other differences between the SoMs are missing SPI-NOR on
this SoM and 1.8V IO voltage instead of 3.3V as found on the existing
imx8mp-phycore-som. As a result the imx8mp-phycore-som is not compatible
with this new libra development board.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Yannic Moog <y.moog@phytec.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>