nfs: remove unused NFS_CALL macro

Nothing uses this, and thank goodness, as the syntax looks horrid.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

include/linux/nfs_xdr.h

@@ -1820,13 +1820,6 @@ struct nfs_rpc_ops {
 	void	(*disable_swap)(struct inode *inode);
 };
 
-/*
- * 	NFS_CALL(getattr, inode, (fattr));
- * into
- *	NFS_PROTO(inode)->getattr(fattr);
- */
-#define NFS_CALL(op, inode, args)	NFS_PROTO(inode)->op args
-
 /*
  * Function vectors etc. for the NFS client
  */