i965: Move prog_data uniform setup to the codegen level

i965: Move prog_data uniform setup to the codegen level

As of now, uniform setup is more-or-less unified between vec4 and fs and no
longer requires the fs_visitor.  This makes uniform setup more of a
language/API thing than a backend compiler thing.  This commit moves
setting up the stage_prog_data.params arrays to the same place as we set up
the rest of stage_prog_data.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>