mediafoundation: don't send METransformNeedInput when in Flush/Drain

Reviewed-by: Rohit Athavale <rathavale@microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36082>

src/gallium/frontends/mediafoundation/mftransform.cpp

@@ -1413,7 +1413,7 @@ CDX12EncHMFT::xThreadProc( void *pCtx )
          pThis->m_eventInputDrained.set();
       }
       pThis->m_eventHaveInput.reset();
-      if( !pThis->m_bLowLatency )
+      if( !pThis->m_bLowLatency && !pThis->m_bFlushing && !pThis->m_bDraining )
       {
          pThis->m_dwNeedInputCount++;
          HRESULT hr = pThis->QueueEvent( METransformNeedInput, GUID_NULL, S_OK, nullptr );