Paritally fix depth read elf

Paritally fixes https://github.com/DHrpcs3/rpcs3/issues/330 by setting scissor and should now look better . However the scale is still wrong and need to revert 3c8815c for full functionality.

I tried to build using commit before 3c8815c , it is prefectly fine then .

![untitled](https://cloud.githubusercontent.com/assets/3000282/3281747/a91544e4-f4c0-11e3-9bcc-36d4491b7018.jpg)