The generic bootscript is tailored around a downstream firmware and
doesn't work on a firmware built from mainline components.
Add a bootscript which:
* sets $console since mainline u-boot doesn't do that
* uses distro boot variables, so OpenWRT can be booted off any supported
device when using a mainline firmware
* sets missing distro boot variables for the downstream firmware
Booting with a downstream firmware is unchanged.
Booting with a mainline firmware now works.
Signed-off-by: Andre Heider <a.heider@gmail.com>
