dquot: cleanup dquot drop routine

Get rid of the drop dquot operation - it is now always called from
the filesystem and if a filesystem really needs it's own (which none
currently does) it can just call into it's own routine directly.

Rename the now static low-level dquot_drop helper to __dquot_drop
and vfs_dq_drop to dquot_drop to have a consistent namespace.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index 859389a..1199e8e 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -109,7 +109,7 @@
 			(unsigned long long)iinfo->i_lenExtents);
 	}
 
-	vfs_dq_drop(inode);
+	dquot_drop(inode);
 	kfree(iinfo->i_ext.i_data);
 	iinfo->i_ext.i_data = NULL;
 }