Revert a25a9d4: temporary fix for chroma upsampling on AMD. 

Hi,
I think we should revert this "temporary fix" and use the same surface for all vendors for consistency. 

I was affected back then, I even wrote about the problem on doom9. But now everything works fine. I did test on 12.10 (WHQL) and 12.11 (Beta11) drivers and the problem apparently was fixed.  No need to keep workarounds when they are not needed.

Regards