isdn/gigaset: fix leaks in error path

Take care to free all previously allocated ressources in the
"out of memory" error path of the ISDN_CMD_DIAL branch.
Based on an original patch by Dan Carpenter.

Impact: bugfix
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Acked-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/gigaset/i4l.c

@@ -419,6 +419,8 @@ oom:
 	dev_err(bcs->cs->dev, "out of memory\n");
 	for (i = 0; i < AT_NUM; ++i)
 		kfree(commands[i]);
+	kfree(commands);
+	gigaset_free_channel(bcs);
 	return -ENOMEM;
 }