ocfs2: clear unaligned io flag when dio fails

The unaligned io flag is set in the kiocb when an unaligned
dio is issued, it should be cleared even when the dio fails,
or it may affect the following io which are using the same
kiocb.

Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Joel Becker <jlbec@evilplan.org>