Avoid sending PHYDISK_HIDDEN RAID action requests to SAS2 controllers
since they don't support it.

Also enable fast_path only for SAS3 HBAs.
Signed-off-by: NSreekanth Reddy <Sreekanth.Reddy@avagotech.com>
Acked-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>