Interrupt storm on acpi0 occurred after madt.c change

[Nate Lawson]

Actually, after looking at Peter's MADT, it appears it does have an
override from 9 to 20 with the polarity "conforming" and level-triggered.
I assume that conforming means low for his system.

In this case, the only thing to do is blacklist his machine and force it
to MPtable evaluation.  I've been thinking about incorporating a similar
blacklist feature to NetBSD and Linux.  Please email me privately to make
sure it can meet your needs.

-Nate