This patch adds support for emmc on my sopine+baseboard, dmesg added
I am still struggeling with putting u-boot on the emmc. I have exactly one
u-boot version that boots from emmc but after starting the efi bootloader
it does not see any disks and falls back to tftp boot which is not (yet)
working. If I boot the same version from sdcard the process works. The
version of the working u-boot is 2018.03, the newer ones from
sysutils/u-boot won't boot to the command line but keep resetting after
printing the u-boot SPL banner.