code review fix

Change-Id: Ie616543094aaa31d596980ba7a3cef05de4351fc
diff --git a/src/challenge/challenge-pin.cpp b/src/challenge/challenge-pin.cpp
index 26e5317..5d3ea8a 100644
--- a/src/challenge/challenge-pin.cpp
+++ b/src/challenge/challenge-pin.cpp
@@ -105,7 +105,7 @@
 
 Block
 ChallengePin::genChallengeRequestTLV(Status status, const std::string& challengeStatus,
-                                     std::multimap<std::string, std::string>&& params)
+                                     const std::multimap<std::string, std::string>& params)
 {
   Block request(tlv::EncryptedPayload);
   if (status == Status::BEFORE_CHALLENGE) {