config: Save multiplayer settings only globally

Saved multiplayer settings like the nickname, remote address, etc. were reset everytime a game was booted up and the game-specific config files were loaded, as these values will never be set.

src/yuzu/configuration/config.cpp

@@ -941,7 +941,6 @@ void Config::ReadValues() {
     ReadRendererValues();
     ReadAudioValues();
     ReadSystemValues();
-    ReadMultiplayerValues();
 }
 
 void Config::SavePlayerValue(std::size_t player_index) {
@@ -1099,7 +1098,6 @@ void Config::SaveValues() {
     SaveRendererValues();
     SaveAudioValues();
     SaveSystemValues();
-    SaveMultiplayerValues();
 }
 
 void Config::SaveAudioValues() {