[9fans] kirkwood (sheevaplug) configuration changes

[geoff@plan9.bell-labs.com]

I've just pushed changed kirkwood kernel sources to sources.
The main visible changes are that the kirkwood kernel will now
parse a plan9.ini file found in low memory and will write its
#ec contents there just before a reboot, thus preserving them
for the next kernel.  Now that this is possible, the compiled-in
sheevaplug configuration variables have been removed from the
kernel.  See plug.words for the new boot commands to load
/cfg/pxe/$ether into low memory, and cfg-pxe-example for
configuration variables that you're likely to need.

There's been no significant progress on usb, flash access nor
write-back l2 cache, despite several of us banging our heads
against usb and cache walls.