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/reiserfs/inode.c b/fs/reiserfs/inode.c
index 99a5e5a..f07c3b6 100644
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -1964,7 +1964,7 @@
       out_end_trans:
 	journal_end(th, th->t_super, th->t_blocks_allocated);
 	/* Drop can be outside and it needs more credits so it's better to have it outside */
-	vfs_dq_drop(inode);
+	dquot_drop(inode);
 	inode->i_flags |= S_NOQUOTA;
 	make_bad_inode(inode);