md/raid1: discard unused variable.

This structure field (flushing_bio_list) is never used, so remove it.
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid1.c

@@ -1966,7 +1966,6 @@ static conf_t *setup_conf(mddev_t *mddev)
 	init_waitqueue_head(&conf->wait_barrier);
 
 	bio_list_init(&conf->pending_bio_list);
-	bio_list_init(&conf->flushing_bio_list);
 
 	conf->last_used = -1;
 	for (i = 0; i < conf->raid_disks; i++) {

drivers/md/raid1.h

@@ -35,8 +35,6 @@ struct r1_private_data_s {
 	struct list_head	retry_list;
 	/* queue pending writes and submit them on unplug */
 	struct bio_list		pending_bio_list;
-	/* queue of writes that have been unplugged */
-	struct bio_list		flushing_bio_list;
 
 	/* for use when syncing mirrors: */