radioInterfaceMulti: Override setTxGain() to avoid chan!=0 calls

Change-Id: I7e67f660c3b0b009db59b405de603f6058021802
diff --git a/Transceiver52M/radioInterface.cpp b/Transceiver52M/radioInterface.cpp
index 9c7c044..6e49a75 100644
--- a/Transceiver52M/radioInterface.cpp
+++ b/Transceiver52M/radioInterface.cpp
@@ -112,7 +112,7 @@
   if (atten < 0.0)
     atten = 0.0;
 
-  rfGain = mDevice->setTxGain(mDevice->maxTxGain() - (double) atten, chan);
+  rfGain = setTxGain(mDevice->maxTxGain() - (double) atten, chan);
   digAtten = (double) atten - mDevice->maxTxGain() + rfGain;
 
   if (digAtten < 1.0)
@@ -307,6 +307,11 @@
   return mDevice->setRxGain(dB, chan);
 }
 
+double RadioInterface::setTxGain(double dB, size_t chan)
+{
+  return mDevice->setTxGain(dB, chan);
+}
+
 /* Receive a timestamped chunk from the device */
 int RadioInterface::pullBuffer()
 {