m68k: remove old mac_esp cruft

Remove the rest of the old mac_esp driver. Also ditch the rest of the
machw mechanism, it needs to be replaced by a fake openfirmware tree.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>