Pull up following revision(s) (requested by mhitch in ticket #1166):
sys/arch/amiga/amiga/machdep.c: revision 1.222
Remove old legacy IPL_* settings in ipl2spl_table - they are redundant
and in the case of IPL_AUDIO, results in IPL_VM blocking all interrupts.
[IPL_AUDIO is now the same as IPL_VM, and was setting the IPL_VM entry
to PSL_IPL6.  IPL_SERIAL had a duplicate entry for some reason, and
serial drivers that check and modify IPL_SERIAL now shouldn't be affected
since IPL_SERIAL is now the same as IPL_HIGH.  I'm hoping this will fix
or at least help the problem of serial interrupts being blocked too long.

(snj)