rapidio: devices: fix missing put_device in mport_cdev_open

When kfifo_alloc fails, the refcount of chdev->dev is left incremental.
We should use put_device(&chdev->dev) to decrease the ref count of
chdev->dev to avoid refcount leak.

Link: https://lkml.kernel.org/r/[e-mail]
Fixes: e8de370188d0 ("rapidio: add mport char device driver")
Signed-off-by: Cai Xinchen <[e-mail]>
Cc: Alexandre Bounine <[e-mail]>
Cc: Dan Carpenter <[e-mail]>
Cc: Jakob Koschel <[e-mail]>
Cc: John Hubbard <[e-mail]>
Cc: Matt Porter <[e-mail]>
Cc: Wang Weiyang <[e-mail]>
Cc: Yang Yingliang <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

drivers/rapidio/devices/rio_mport_cdev.c

···
 			  sizeof(struct rio_event) * MPORT_EVENT_DEPTH,
 			  GFP_KERNEL);
 	if (ret < 0) {
+		put_device(&chdev->dev);
 		dev_err(&chdev->dev, DRV_NAME ": kfifo_alloc failed\n");
 		ret = -ENOMEM;
 		goto err_fifo;