Previously ownerboot had separate `userspace` (the initramfs
contents without kernel modules) and `initramfs` (the complete
initramfs) expressions. This was done in order to allow the use of
CONFIG_INITRAMFS_SOURCE, which links an initramfs image into the
kernel itself.
I did this because I was having a hard time getting coreboot to load
a separate initrd on rk3399. I have since solved that problem, and
am now using coreboot to load an initramfs on all platforms. There
is no longer any need for this unusual separation.