message: Fix validation on minting zerocoin tx for GUI
diff: @@ -1484,7 +1484,7 @@ bool CWallet::CreateZerocoinMintModel(string &stringError, string denomAmount){
  CZerocoinEntry zerocoinTx;
  zerocoinTx.IsUsed = false;
  - zerocoinTx.denomination = 1;
  + zerocoinTx.denomination = denomination;
  zerocoinTx.value = pubCoin.getValue();
  zerocoinTx.randomness = newCoin.getRandomness();
  zerocoinTx.serialNumber = newCoin.getSerialNumber();
  