Follow changes to other OrangePi boards, most importantly
orangepi-zero-plus2, which this board support is based on. This includes
switching to extlinux as boot mechanism and dropping custom U-Boot boot
script.
Rootfs image no longer fits into default 60M (mostly due to Linux
modules), so increase it to 120M.
While at it, bump Linux to 6.1.4 and U-Boot to 2023.01.
Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
