drivers/block/cciss.c: fix check-after-use

The Coverity checker spotted that we have already oops'ed if "disk"
was NULL.

Since "disk" being NULL seems impossible at this point this patch
removes the NULL check.
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Acked-by: NMike Miller <mike.miller@hp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/block/cciss.c

@@ -1582,7 +1582,6 @@ static int deregister_disk(struct gendisk *disk, drive_info_struct *drv,
 	 * allows us to delete disk zero but keep the controller registered.
 	 */
 	if (h->gendisk[0] != disk) {
-		if (disk) {
 		struct request_queue *q = disk->queue;
 		if (disk->flags & GENHD_FL_UP)
 			del_gendisk(disk);
@@ -1614,7 +1613,6 @@ static int deregister_disk(struct gendisk *disk, drive_info_struct *drv,
 			}
 			put_disk(disk);
 		}
-		}
 	} else {
 		set_capacity(disk, 0);
 	}