loop: Remove duplicate assignments

The assignment and operation there will be overwritten later, so
it should be deleted.

The clang_analyzer complains as follows:

drivers/block/loop.c:2330:2 warning:

Value stored to 'err' is never read

change in v2:

Repair the sending email box
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: luo penghao <luo.penghao@zte.com.cn>
Link: https://lore.kernel.org/r/20211104064546.3074-1-luo.penghao@zte.com.cnSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/loop.c

@@ -2003,7 +2003,6 @@ static int loop_add(int i)
 		goto out_free_dev;
 	i = err;
 
-	err = -ENOMEM;
 	lo->tag_set.ops = &loop_mq_ops;
 	lo->tag_set.nr_hw_queues = 1;
 	lo->tag_set.queue_depth = 128;