ataflop: fix off by one in ataflop_probe()

Smatch complains that the "type > NUM_DISK_MINORS" should be >=
instead of >.  We also need to subtract one from "type" at the start.

Fixes: bf9c0538 ("ataflop: use a separate gendisk for each media format")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/ataflop.c

@@ -2001,7 +2001,10 @@ static void ataflop_probe(dev_t dev)
 	int drive = MINOR(dev) & 3;
 	int type  = MINOR(dev) >> 2;
 
-	if (drive >= FD_MAX_UNITS || type > NUM_DISK_MINORS)
+	if (type)
+		type--;
+
+	if (drive >= FD_MAX_UNITS || type >= NUM_DISK_MINORS)
 		return;
 	mutex_lock(&ataflop_probe_lock);
 	if (!unit[drive].disk[type]) {