m68k: Mac interrupt priorities

Add some more machines that support A/UX interrupt priorities. There are
probably others as well, but I've only tested these ones so far.

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>