ocfs2: add missing errno in ocfs2_ioctl_move_extents()

If the file is not regular or writeable, it should return errno(EPERM).

This patch is based on 85a258b7 ("ocfs2: fix error handling in
ocfs2_ioctl_move_extents()").

Signed-off-by: Younger Liu <younger.liu@huawei.com>
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Jie Liu <jeff.liu@oracle.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>