Update the google-tv-pairing-protocol polo.proto to use the
deprecated nano package.

This fixes the build breakage that will be caused by
I0b930811a3a8240c236d3708d51f11bc04241593

Change-Id: Ib5fb2eabbe3932bf1cc9046559d8a0de9cad082a
diff --git a/proto/polo.proto b/proto/polo.proto
index fbe95e9..0491439 100644
--- a/proto/polo.proto
+++ b/proto/polo.proto
@@ -2,6 +2,7 @@
 
 package polo.wire.protobuf;
 
+option javanano_use_deprecated_package = true;
 option java_outer_classname = "PoloProto";
 option java_package = "com.google.polo.wire.protobuf";
 option optimize_for = LITE_RUNTIME;