dquot: move dquot drop responsibility into the filesystem

Currently clear_inode calls vfs_dq_drop directly.  This means
we tie the quota code into the VFS.  Get rid of that and make the
filesystem responsible for the drop inside the ->clear_inode
superblock operation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/inode.c

@@ -108,6 +108,8 @@ void udf_clear_inode(struct inode *inode)
 			(unsigned long long)inode->i_size,
 			(unsigned long long)iinfo->i_lenExtents);
 	}
+
+	vfs_dq_drop(inode);
 	kfree(iinfo->i_ext.i_data);
 	iinfo->i_ext.i_data = NULL;
 }