please test - ATA bugfixes

[Nate Lawson]

Please test ATA in -current if you had one of the following problems:

1. "Memory modified after free" panic with invariants and Thinkpad DVD, 
CD, CDRW, etc. drive
2. Long (30 second) delay on resume

It would also be nice to know if anyone finds a regression (not likely.) 
  Matt Dodd was kind enough to commit the patches.  It would be good to 
give them as much testing as possible.

Thanks,
-- 
Nate