This simplifies the uboot script and updates it to use correct address
offsets for kernel, ramdisk and fdt. Appending the dtb to the kernel is
no longer necessary. This also changes the dtb to the one used on
PureOS.
We don't need to append the dtb to the kernel image in all cases, with
e.g. the u-boot bootloader we can load the dtb seperately from the
kernel image. Introduce a new variable deviceinfo_append_dtb, if set to
"true", append the dtb, otherwise just copy the dtb file to the boot
partition.
Fixes#260
[ci:ignore-count]
Since a recent kernel update enables the LCD display, this
uses a dts that allows the lcd to function, but drops support
for usb host (since purism does not have an all-in-one dts
yet)
[skip ci]: already built successfully in CI
USB host mode is useful (essential?) on the devkit for adding a
keyboard/mouse to interact with the desktop since the onboard display
and touchscreen are very much in flux.
[skip ci]: already built successfully in CI
