libata: Support SATA attached via SAS

Jeff,

Here are the remaining 2 patches to my patchset to allow SAS HBAs to use libata to control attached SATA devices. The last two issues you brought up have been addressed as follows:

1. Per device max command length checking
- This has been removed.

2. Add ata_host_flags
- You thought there might be a need to carry some cross port state. To resolve this I added a new API: ata_host_set_init. Callers of ata_sas_port_alloc must now pass their host_set pointer as the first argument. This removes the need for the patch you objected to and allows for a cross port state if needed.

Brian King
eServer Storage I/O
IBM Linux Technology Center