nfs: remove unused writeverf code

Remove duplicate writeverf structure from merge of nfs_pgio_header and
nfs_pgio_data and remove writeverf related flags and logic to handle
more than one RPC per nfs_pgio_header.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index ecb3d4c..7dd0d5f 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -545,7 +545,7 @@
 	hdr->res.fattr   = &hdr->fattr;
 	hdr->res.count   = count;
 	hdr->res.eof     = 0;
-	hdr->res.verf    = &hdr->writeverf;
+	hdr->res.verf    = &hdr->verf;
 	nfs_fattr_init(&hdr->fattr);
 }