xfs: get rid of indirections in the quotaops implementation

Currently we call from the nicely abstracted linux quotaops into a ugly
multiplexer just to split the calls out at the same boundary again.
Rewrite the quota ops handling to remove that obfucation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
diff --git a/fs/xfs/xfs_quota.h b/fs/xfs/xfs_quota.h
index 63d41ac..f5d1202 100644
--- a/fs/xfs/xfs_quota.h
+++ b/fs/xfs/xfs_quota.h
@@ -18,6 +18,8 @@
 #ifndef __XFS_QUOTA_H__
 #define __XFS_QUOTA_H__
 
+struct xfs_trans;
+
 /*
  * The ondisk form of a dquot structure.
  */