Add support for OF-LIST to common imx8mp-u-boot.dtsi so that it can be used with boards that have multiple DTB's. Signed-off-by: Tim Harvey <tharvey@gateworks.com> Cc: Fabio Estevam <festevam@gmail.com> Cc: NXP i.MX U-Boot Team <uboot-imx@nxp.com> Cc: Peng Fan <peng.fan@nxp.com> Cc: Teresa Remmet <t.remmet@phytec.de> Cc: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org> Cc: Marcel Ziswiler <marcel.ziswiler@toradex.com> Reviewed-by: Fabio Estevam <festevam@denx.de>