scsi: hisi_sas: consolidate command check in hisi_sas_get_ata_protocol()

Currently we check the fis->command value in 2 locations in
hisi_sas_get_ata_protocol() switch statement. Fix this by consolidating
the check for fis->command value to 1 location only.

Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>