sceScreenshot : pass paramAddr into screenshotDialog.Init();

Should help https://github.com/hrydgard/ppsspp/issues/5779 to go in-game now instead of black screen.

![uljs00333_00001](https://cloud.githubusercontent.com/assets/3000282/2806611/c9a549a4-cccd-11e3-8836-21d8922c6ef2.jpg)