shared_page: Allow Setting the 3D Slider

Currently, changing the Option while the Game is running does not work

src/core/hle/shared_page.cpp

@@ -97,4 +97,8 @@ void Set3DLed(u8 state) {
     shared_page.ledstate_3d = state;
 }
 
+void Set3DSliderState(float_le state) {
+    shared_page.sliderstate_3d = state;
+}
+
 } // namespace SharedPage

src/core/hle/shared_page.h

@@ -84,4 +84,6 @@ void SetWifiLinkLevel(WifiLinkLevel);
 
 void Set3DLed(u8);
 
+void Set3DSliderState(float_le);
+
 } // namespace SharedPage