sun68k/include/intr.h.
This also means now sun3 has GENERIC_SOFT_INTERRUPTS support,
so also adapt fd.c and zs.c to MI softintr(9) APIs.
(I'll also update related sources in yamt-splraiseipl branch later)
- make sun3 port use common sun68k files as much as possible
- add temporary options _SUN2_ in std.sun2 until sun3 can share all
sun68k files (autoconf.c and isr.c are not yet)
- move sun68kvme declaration temporary as well from files.sun68k to files.sun2
- rename and move sun68k_find_prom_map() function to MD sources since it
can't be shared with sun3
- add bus tag members to struct confargs and initilize them where appropriate
XXX1: MD bus_dma(9) backends are not implemented (yet).
XXX2: more code (obio etc.) should be shared among sun3, sun3x and sun2.
