ocfs2: Fix some typos in xattr annotations.

Fix some typos in the xattr annotations.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
Reported-by: Coly Li <coyli@suse.de>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>