block: remove ->driverfs_dev

Now that all drivers that specify a ->driverfs_dev have been converted
to device_add_disk(), the pointer can be removed from struct gendisk.

Cc: Jens Axboe <axboe@fb.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/block/genhd.c b/block/genhd.c
index fb2d9ae..a18d353 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -618,10 +618,6 @@
 
 	blk_register_region(disk_devt(disk), disk->minors, NULL,
 			    exact_match, exact_lock, disk);
-
-	/* temporary while we convert usages to use disk_to_dev(disk)->parent */
-	disk->driverfs_dev = parent;
-
 	register_disk(parent, disk);
 	blk_register_queue(disk);
 
@@ -804,10 +800,9 @@
 			       , disk_name(disk, part->partno, name_buf),
 			       part->info ? part->info->uuid : "");
 			if (is_part0) {
-				if (disk->driverfs_dev != NULL &&
-				    disk->driverfs_dev->driver != NULL)
+				if (dev->parent && dev->parent->driver)
 					printk(" driver: %s\n",
-					      disk->driverfs_dev->driver->name);
+					      dev->parent->driver->name);
 				else
 					printk(" (driver?)\n");
 			} else