scsi: remove the disable_blk_mq host flag

We've had scsi-mq for 2.5 years now, so we can remove the unused flag to
disable the code on a per-host basis that was put in for unexpected
emergencies during bringup.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 1deb6ad..1f36aca 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -1160,6 +1160,7 @@
 bool scsi_use_blk_mq = false;
 #endif
 module_param_named(use_blk_mq, scsi_use_blk_mq, bool, S_IWUSR | S_IRUGO);
+EXPORT_SYMBOL_GPL(scsi_use_blk_mq);
 
 static int __init init_scsi(void)
 {