cifs: Fix xid leak in cifs_copy_file_range()

If the file is used by swap, before return -EOPNOTSUPP, should
free the xid, otherwise, the xid will be leaked.

Fixes: 4e8aea30

 ("smb3: enable swap on SMB3 mounts")
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>