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/ext4/super.c b/fs/ext4/super.c
index 56554c8..035516c8 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -761,7 +761,7 @@
 
 static void ext4_clear_inode(struct inode *inode)
 {
-	vfs_dq_drop(inode);
+	dquot_drop(inode);
 	ext4_discard_preallocations(inode);
 	if (EXT4_JOURNAL(inode))
 		jbd2_journal_release_jbd_inode(EXT4_SB(inode->i_sb)->s_journal,
@@ -1014,7 +1014,6 @@
 
 static const struct dquot_operations ext4_quota_operations = {
 	.initialize	= dquot_initialize,
-	.drop		= dquot_drop,
 #ifdef CONFIG_QUOTA
 	.get_reserved_space = ext4_get_reserved_space,
 #endif