[SCSI] libsas: fix NCQ mixing with non-NCQ

Some cards (like mvsas) have issue troubles if non-NCQ commands are
mixed with NCQ ones.  Fix this by using the libata default NCQ check
routine which waits until all NCQ commands are complete before issuing
a non-NCQ one.  The impact to cards (like aic94xx) which don't need
this logic should be minimal

Cc: Stable Tree <stable@kernel.org>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>

drivers/scsi/libsas/sas_ata.c

@@ -347,6 +347,7 @@ static int sas_ata_scr_read(struct ata_link *link, unsigned int sc_reg_in,
 static struct ata_port_operations sas_sata_ops = {
 	.phy_reset		= sas_ata_phy_reset,
 	.post_internal_cmd	= sas_ata_post_internal,
+	.qc_defer               = ata_std_qc_defer,
 	.qc_prep		= ata_noop_qc_prep,
 	.qc_issue		= sas_ata_qc_issue,
 	.qc_fill_rtf		= sas_ata_qc_fill_rtf,