Merge C20 on develop
C20 is based on imx8mq/imx8md/imx8mq-lite SoC and designed to support Low Power DDR3 RAM.
modified: arch/arm64/boot/dts/seco/Makefile
new file: arch/arm64/boot/dts/seco/include/imx8mq-pinfunc.h
new file: arch/arm64/boot/dts/seco/include/seco-imx8mq.dtsi
new file: arch/arm64/boot/dts/seco/seco-imx8mq-c20.dts