svc: Add a max payload value to the transport

The svc_max_payload function currently looks at the socket type
to determine the max payload. Add a max payload value to svc_xprt_class
so it can be returned directly.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Neil Brown <neilb@suse.de>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Greg Banks <gnb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

include/linux/sunrpc/svc_xprt.h

@@ -17,6 +17,7 @@ struct svc_xprt_class {
 	struct module		*xcl_owner;
 	struct svc_xprt_ops	*xcl_ops;
 	struct list_head	xcl_list;
+	u32			xcl_max_payload;
 };
 
 struct svc_xprt {