audio: fixed typo in Doxygen comment.
diff --git a/include/SDL_audio.h b/include/SDL_audio.h
index f119c2b..5516812 100644
--- a/include/SDL_audio.h
+++ b/include/SDL_audio.h
@@ -527,7 +527,7 @@ extern DECLSPEC SDL_AudioStream * SDLCALL SDL_NewAudioStream(const SDL_AudioForm
*
* \param stream The stream the audio data is being added to
* \param buf A pointer to the audio data to add
- * \param int The number of bytes to write to the stream
+ * \param len The number of bytes to write to the stream
* \return 0 on success, or -1 on error.
*
* \sa SDL_NewAudioStream