SUNRPC: Add support for formatted universal addresses

"Universal addresses" are a string representation of an IP address and
port.  They are described fully in RFC 3530, section 2.2.  Add support
for generating them in the RPC client's socket transport module.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 4596c26..902a9c0 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -55,6 +55,7 @@
 	RPC_DISPLAY_ALL,
 	RPC_DISPLAY_HEX_ADDR,
 	RPC_DISPLAY_HEX_PORT,
+	RPC_DISPLAY_UNIVERSAL_ADDR,
 	RPC_DISPLAY_MAX,
 };