remotetcpinput: Avoid using uninitialized converter buffer

Coverity reported that an invalid sample size could leave the
conversion buffer uninitialized before it was passed to calcPower()
and the sample FIFO.

Return early when the sample conversion format is unsupported to
prevent processing invalid data.

Signed-off-by: Robin Getz <rgetz503@gmail.com>

plugins/samplesource/remotetcpinput/remotetcpinputtcphandler.cpp

@@ -2231,6 +2231,7 @@ void RemoteTCPInputTCPHandler::processUncompressedData(const char *inBuf, int nb
     else // invalid size
     {
         qWarning("RemoteTCPInputTCPHandler::convert: unexpected sample size in stream: %d bits", (int) m_settings.m_sampleBits);
+        return;
     }
 
     qint32 len = nbSamples*2;