i965: Move binding table setup to codegen time.

i965: Move binding table setup to codegen time.

Setting up binding tables really has little to do with the actual process
of turning shaders into instructions; it's more part of setting up
prog_data.  This commit moves it out of the visitors and with the rest of
the prog_data setup stuff.

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