Now ata devices attached with sas controller do not have transport
class, so that we can not see any information of these ata devices in
/sys/class/ata_port(or ata_link or ata_device).

Add transport class for the ata devices attached with sas controller.
The /sys/class directory will show the infomation of the ata devices
as follows:

localhost:/sys/class # ls ata*
ata_device:
dev1.0  dev2.0

ata_link:
link1  link2

ata_port:
ata1  ata2

No functional change of the device scanning and io path. The ata
transport class was deleted when destroying the sas devices.

Signed-off-by: Jason Yan <yanaijie@huawei.com>
CC: Dan Williams <dan.j.williams@intel.com>
CC: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>