Zhigang Gong authored Jan 19, 2012 and Emma Anholt committed Dec 18, 2013

We classify the cache according to the texture's format/width/height.
As openGL doesn't allow us to change a texture's format/width/height
after the internal texture object is already allocated, we can't
just calculate the size and then according ths size to put the
fbo to an bucket which is just like SNA does. We can only put
the fbo to the corresponding format/width/height bucket.

This commit only support the exact size match. The following patch
will remove this restriction, just need to handle the repeat/tile
case when the size is not exactly match.

Should use fls instead of ffs when decide the width/height bucket,
thanks for Chris to point this out.

Signed-off-by: Zhigang Gong <zhigang.gong@linux.intel.com>