const declaration has no effect

When building with -Wignored-qualifiers, the constness of a returned
pointer (as opposed to the thing being pointed to) is ignored.  This
removes an unnecessary const declaration.

Author: samhansen

src/lib/profiles/time/WeaveTime.h

@@ -1245,7 +1245,7 @@ class NL_DLL_EXPORT SingleSourceTimeSyncClient
     WEAVE_ERROR SendSyncRequest(void);
 
     void SetClientState(const ClientState state);
-    const char * const GetClientStateName(void) const;
+    const char * GetClientStateName(void) const;
 
     static void HandleTimeChangeNotification(ExchangeContext *aEC, const IPPacketInfo *aPktInfo,
         const WeaveMessageInfo *aMsgInfo, uint32_t aProfileId, uint8_t aMsgType, PacketBuffer *aPayload);

src/lib/profiles/time/WeaveTimeClient.cpp

@@ -2669,7 +2669,7 @@ void SingleSourceTimeSyncClient::HandleTimeChangeNotification(ExchangeContext *a
     }
 }
 
-const char * const SingleSourceTimeSyncClient::GetClientStateName(void) const
+const char * SingleSourceTimeSyncClient::GetClientStateName(void) const
 {
     const char * stateName = NULL;