MPC5200 support

[Robert Swindells <rjs%fdy2.demon.co.uk@localhost>]

I have put a tarball of new files and diffs on ftp.n.o that add some
support for the MPC5200 processor on the Efika board.

So far it boots to single user mode using a PCI Ethernet card and the
serial console.

A review would be welcome. I haven't debugged the uart driver yet so
the diffs contain code copied from sys/dev/ofw/ofcons.c, I'm not
planning on committing this part.

Testing some of the diffs against macppc to see that I haven't broken
anything would be helpful too.

The path is ftp.netbsd.org:/pub/NetBSD/misc/rjs/evika.tar.gz

Robert Swindells