sata_nv: set host can_queue count appropriately

libata limits the max limit for drivers to 31 anyway. We'll soon
allow drivers to actually go to QD=32, but that might require some
driver modifications. Before we do that, ensure that sata_nv limits
the depth to 31.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tejun Heo <tj@kernel.org>

drivers/ata/sata_nv.c

@@ -400,7 +400,7 @@ static struct scsi_host_template nv_adma_sht = {
 
 static struct scsi_host_template nv_swncq_sht = {
 	ATA_NCQ_SHT(DRV_NAME),
-	.can_queue		= ATA_MAX_QUEUE,
+	.can_queue		= ATA_MAX_QUEUE - 1,
 	.sg_tablesize		= LIBATA_MAX_PRD,
 	.dma_boundary		= ATA_DMA_BOUNDARY,
 	.slave_configure	= nv_swncq_slave_config,