Remove unused audio namespace and clean up includes in APU and DSP files

src/app/emu/audio/spc700.h

@@ -3,13 +3,10 @@
 
 #include <cstdint>
 #include <functional>
-#include <iostream>
-#include <unordered_map>
 #include <vector>
 
 namespace yaze {
 namespace emu {
-namespace audio {
 
 /**
  * @brief AudioRam is an interface for the Audio RAM used by the SPC700.
@@ -336,8 +333,7 @@ class Spc700 {
   // CBNE DBNZ
 };
 
-}  // namespace audio
 }  // namespace emu
-
 }  // namespace yaze
-#endif  // YAZE_APP_EMU_SPC700_H
+
+#endif  // YAZE_APP_EMU_SPC700_H