Correct the comments for radio hal types

The type of mcc and mnc is String instead of Int now. They should be an
empty string if unknown. Also added a test case for their values.

Bug: 111703979
Test: Vts
Change-Id: Ie0426453dc426ccc6cf203b315806e78511ce14d
diff --git a/radio/1.0/vts/functional/radio_response.cpp b/radio/1.0/vts/functional/radio_response.cpp
index 93d5557..f3938a9 100644
--- a/radio/1.0/vts/functional/radio_response.cpp
+++ b/radio/1.0/vts/functional/radio_response.cpp
@@ -157,8 +157,9 @@
 }
 
 Return<void> RadioResponse::getDataRegistrationStateResponse(
-    const RadioResponseInfo& info, const DataRegStateResult& /*dataRegResponse*/) {
+    const RadioResponseInfo& info, const DataRegStateResult& dataRegResponse) {
     rspInfo = info;
+    dataRegResp = dataRegResponse;
     parent.notify(info.serial);
     return Void();
 }