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/ialloc.c b/fs/udf/ialloc.c
index e1856b8..15c6e99 100644
--- a/fs/udf/ialloc.c
+++ b/fs/udf/ialloc.c
@@ -37,7 +37,7 @@
 	 * as writing the quota to disk may need the lock as well.
 	 */
 	dquot_free_inode(inode);
-	vfs_dq_drop(inode);
+	dquot_drop(inode);
 
 	clear_inode(inode);
 
@@ -156,7 +156,7 @@
 	vfs_dq_init(inode);
 	ret = dquot_alloc_inode(inode);
 	if (ret) {
-		vfs_dq_drop(inode);
+		dquot_drop(inode);
 		inode->i_flags |= S_NOQUOTA;
 		inode->i_nlink = 0;
 		iput(inode);