This removes u-boot from our image and allows booting via an
UEFI-compatible platform firmware instead. So to flash pmOS on the PPP
now we will require the user to flash Tow-Boot to the SPI. See the edge
post for more information.
Related: https://postmarketos.org/edge/2022/03/28/ppp-tow-boot/
Co-Authored-By: Oliver Smith <ollieparanoid@postmarketos.org>
