NFS: Fix initialisation of I/O result struct in nfs_pgio_rpcsetup

Initialise the result count to 0 rather than initialising it to the
argument count. The reason is that we want to ensure we record the
I/O stats correctly in the case where an error is returned (for
instance in the layoutstats).
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/pagelist.c

@@ -590,7 +590,7 @@ static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 	}
 
 	hdr->res.fattr   = &hdr->fattr;
-	hdr->res.count   = count;
+	hdr->res.count   = 0;
 	hdr->res.eof     = 0;
 	hdr->res.verf    = &hdr->verf;
 	nfs_fattr_init(&hdr->fattr);