instantiate directly altera dpram component instead of generic

Generic memory instantiation as is described in generic_dpram_mod can only be synthesized with bus width such, that maximum 5000 elements is generated. This limitation comes from quartus, who does not allow to unroll a loop of more than 5000 iterations. Compilation in this case fails.

As this component is used exclusively in Altera developments, this patch comments out generic memory block description, and replaces it by altera megafunction, which correctly instantiates memories regardless of the width of the address bus