amd64/89550: spin-lock panics continue (crash trace)

[Mikhail Teterin]

The patch in the PR allows our two Symbios 875 boards to work with 
FreeBSD-6.2-recent.

However, the machine continues to suffer from the "spin lock held to long" 
panics every few days. Usually, there is a double-panic, which prevents crash 
dump from occuring. But this morning it succeeded.

The full trace is available at

	http://aldan.algebra.com/~mi/bonkers-crash-4.txt

The panic is from kern_mutex.c. The value of the delay-counting i is, no 
surprise, exactly 60000000.

I'm not sure, if it is the sym-enabling patch, that causes the problem, or 
something else. Either way, it would be very useful for an expert to look at 
it -- and commit the (possibly modified) patch too.

	-mi