mtd: blktrans: change blktrans_getgeo return value

Modify function blktrans_getgeo()'s return value to -EOPNOTSUPP when
dev->tr->getgeo == NULL.

We shouldn't make the return value to 0 when dev->tr->getgeo == NULL,
because the function blktrans_getgeo() has an output value "hd_geometry"
which is usually used by some application, if returns 0 (i.e.,
"success"), it will make some application get the wrong information.
Signed-off-by: Wenlin Kang <wenlin.kang@windriver.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/mtd_blkdevs.c

@@ -278,7 +278,7 @@ static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 	if (!dev->mtd)
 		goto unlock;
 
-	ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
+	ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -EOPNOTSUPP;
 unlock:
 	mutex_unlock(&dev->lock);
 	blktrans_dev_put(dev);