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/[email protected]
Fixes: e8de370 ("rapidio: add mport char device driver")
Signed-off-by: Cai Xinchen <[email protected]>
Cc: Alexandre Bounine <[email protected]>
Cc: Dan Carpenter <[email protected]>
Cc: Jakob Koschel <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Matt Porter <[email protected]>
Cc: Wang Weiyang <[email protected]>
Cc: Yang Yingliang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Caixinchen1

drivers/rapidio/devices/rio_mport_cdev.c

@@ -1912,6 +1912,7 @@ static int mport_cdev_open(struct inode *inode, struct file *filp)
 			  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;