SUNRPC: use sockaddr + size when creating remote transport endpoints

Prepare for more generic transport endpoint handling needed by transports
that might use different forms of addressing, such as IPv6.

Introduce a single function call to replace the two-call
xprt_create_proto/rpc_create_client API.  Define a new rpc_create_args
structure that allows callers to pass in remote endpoint addresses of
varying length.

Test-plan:
Compile kernel with CONFIG_NFS enabled.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index fc05cfb..bc80fcf 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -237,6 +237,7 @@
 /*
  * Generic internal transport functions
  */
+struct rpc_xprt *	xprt_create_transport(int proto, struct sockaddr *addr, size_t size, struct rpc_timeout *toparms);
 void			xprt_connect(struct rpc_task *task);
 void			xprt_reserve(struct rpc_task *task);
 int			xprt_reserve_xprt(struct rpc_task *task);