anv: Put image params in the descriptor set buffer on gen8 and earlier

anv: Put image params in the descriptor set buffer on gen8 and earlier

This is really where they belong; not push constants.  The one downside
here is that we can't push them anymore for compute shaders.  However,
that's a general problem and we should figure out how to push descriptor
sets for compute shaders.  This lets us bump MAX_IMAGES to 64 on BDW and
earlier platforms because we no longer have to worry about push constant
overhead limits.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>