svcrdma: Another sendto chunk list parsing update

Commit 5fdca6531434 ("svcrdma: Renovate sendto chunk list parsing")
missed a spot. svc_rdma_xdr_get_reply_hdr_len() also assumes the
Write list has only one Write chunk. There's no harm in making this
code more general.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/include/linux/sunrpc/rpc_rdma.h b/include/linux/sunrpc/rpc_rdma.h
index cfda6ad..245fc59 100644
--- a/include/linux/sunrpc/rpc_rdma.h
+++ b/include/linux/sunrpc/rpc_rdma.h
@@ -110,6 +110,15 @@ struct rpcrdma_msg {
 };
 
 /*
+ * XDR sizes, in quads
+ */
+enum {
+	rpcrdma_fixed_maxsz	= 4,
+	rpcrdma_segment_maxsz	= 4,
+	rpcrdma_readchunk_maxsz	= 2 + rpcrdma_segment_maxsz,
+};
+
+/*
  * Smallest RPC/RDMA header: rm_xid through rm_type, then rm_nochunks
  */
 #define RPCRDMA_HDRLEN_MIN	(sizeof(__be32) * 7)