SUNRPC: Use "sockaddr_storage" for storing RPC client's remote peer address

IPv6 addresses are big (128 bytes).  Now that no RPC client consumers treat
the addr field in rpc_xprt structs as an opaque, and access it only via the
API calls, we can safely widen the field in the rpc_xprt struct to
accomodate larger addresses.

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/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index e5b19e3..ff1e90f 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -550,7 +550,7 @@
 	if (bytes > bufsize)
 		bytes = bufsize;
 	memcpy(buf, &clnt->cl_xprt->addr, bytes);
-	return sizeof(xprt->addr);
+	return xprt->addrlen;
 }
 EXPORT_SYMBOL(rpc_peeraddr);