ext4: Make Q_GETNEXTQUOTA work for quota in hidden inodes

We forgot to set .get_nextdqblk operation in quotactl_ops structure used
by ext4 when quota is using hidden inode thus the operation was not
really supported. Fix the omission.
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ext4/super.c

@@ -1142,7 +1142,8 @@ static const struct quotactl_ops ext4_qctl_operations = {
 	.get_state	= dquot_get_state,
 	.set_info	= dquot_set_dqinfo,
 	.get_dqblk	= dquot_get_dqblk,
-	.set_dqblk	= dquot_set_dqblk
+	.set_dqblk	= dquot_set_dqblk,
+	.get_nextdqblk	= dquot_get_next_dqblk,
 };
 #endif