[RPC]Fix upper limit check of the number of params

In ElementsProject#515, the assetlabel has been added to two rpc command
(getreceivedbyaddress and getreceivedbylabel) as the 3rd param.
So this patch makes there rpc command accept the 3rd param.

src/wallet/rpcwallet.cpp

@@ -609,7 +609,7 @@ static UniValue getreceivedbyaddress(const JSONRPCRequest& request)
         return NullUniValue;
     }
 
-    if (request.fHelp || request.params.size() < 1 || request.params.size() > 2)
+    if (request.fHelp || request.params.size() < 1 || request.params.size() > 3)
         throw std::runtime_error(
             "getreceivedbyaddress \"address\" ( minconf )\n"
             "\nReturns the total amount received by the given address in transactions with at least minconf confirmations.\n"
@@ -692,7 +692,7 @@ static UniValue getreceivedbylabel(const JSONRPCRequest& request)
         return NullUniValue;
     }
 
-    if (request.fHelp || request.params.size() < 1 || request.params.size() > 2)
+    if (request.fHelp || request.params.size() < 1 || request.params.size() > 3)
         throw std::runtime_error(
             "getreceivedbylabel \"label\" ( minconf )\n"
             "\nReturns the total amount received by addresses with <label> in transactions with at least [minconf] confirmations.\n"