mic_virtio: fix a timeout loop

After the loop we test "if (!retry)" to see if we timedout.  The problem
is "retry--" is a post-op so retry will be -1 at the end of the loop.  I
have fixed this by changing it to a pre-op instead.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mic/card/mic_virtio.c

@@ -337,7 +337,7 @@ static int mic_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 	 * rings have been re-assigned.
 	 */
 	mic_send_intr(mvdev->mdev, mvdev->c2h_vdev_db);
-	for (retry = 100; retry--;) {
+	for (retry = 100; --retry;) {
 		if (!ioread8(&dc->used_address_updated))
 			break;
 		msleep(100);