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/jfs/jfs_inode.c b/fs/jfs/jfs_inode.c
index 7762f33..72b3089 100644
--- a/fs/jfs/jfs_inode.c
+++ b/fs/jfs/jfs_inode.c
@@ -162,7 +162,7 @@
 	return inode;
 
 fail_drop:
-	vfs_dq_drop(inode);
+	dquot_drop(inode);
 	inode->i_flags |= S_NOQUOTA;
 fail_unlock:
 	inode->i_nlink = 0;