I'm trying to build U-Boot (from git.denx.de/u-boot.git). I basically did `make nanopi-r5s-rk3568_defconfig; make` and I'm getting the following message at the end: Image 'simple-bin' is missing external blobs and is non-functional: rockchip-tpl atf-bl31 /binman/simple-bin/mkimage/rockchip-tpl (rock...