sdl2_sink: Distinguish between capture and non-capture device names

The function prototype appears to care whether we are loading capture
devices or not, and SDL_GetAudioDeviceName has a parameter to use it,
but for some reason it isn't.

This puts `capture` where it goes.

src/audio_core/sink/sdl2_sink.cpp

@@ -230,7 +230,7 @@ std::vector<std::string> ListSDLSinkDevices(bool capture) {
 
     const int device_count = SDL_GetNumAudioDevices(capture);
     for (int i = 0; i < device_count; ++i) {
-        const char* name = SDL_GetAudioDeviceName(i, 0);
+        const char* name = SDL_GetAudioDeviceName(i, capture);
         if (name != nullptr) {
             device_list.emplace_back(name);
         }