SiI3531 SATA port multipler

[James R. Van Artsdalen]

Nick Hilliard wrote:
> However, I replaced the SiI3531 with a JMB366 card, and have attached
> the results of a verbose boot.

Looking at the code I think some of the AHCI timeouts are very short. 
Try changing ata_ahci_issue_cmd() to wait at 31 seconds in the command
completion poll loop.  bootverbose will cause it to say how long it
actually took vs. the timeout requested.