brd: get rid of unused members from struct brd_device

brd_refcnt, brd_offset, brd_sizelimit and brd_blocksize in struct
brd_device seem to be copied from struct loop_device but they're
not used anywhere. Let get rid of them.
Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

drivers/block/brd.c

@@ -35,10 +35,6 @@
  */
 struct brd_device {
 	int		brd_number;
-	int		brd_refcnt;
-	loff_t		brd_offset;
-	loff_t		brd_sizelimit;
-	unsigned	brd_blocksize;
 
 	struct request_queue	*brd_queue;
 	struct gendisk		*brd_disk;