Rename RequestState to CaState
 - to prevent confusion with RequesterState

Change-Id: I56048e289fded44bf39dd1fe6a5e26ddd3938b99
diff --git a/src/challenge-modules/challenge-credential.cpp b/src/challenge-modules/challenge-credential.cpp
index 50a15c0..f6e26c2 100644
--- a/src/challenge-modules/challenge-credential.cpp
+++ b/src/challenge-modules/challenge-credential.cpp
@@ -76,7 +76,7 @@
 
 // For CA
 std::tuple<ErrorCode, std::string>
-ChallengeCredential::handleChallengeRequest(const Block& params, RequestState& request)
+ChallengeCredential::handleChallengeRequest(const Block& params, CaState& request)
 {
   params.parse();
   if (m_trustAnchors.empty()) {