0 placeholders for constructor are required by --test-verilog

[yuqisun]

Hi @yo96 ,

As I tested in ControllerRTL.py and TileRTL.py, looks CtrlPktType() instead of CtrlPktType(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) will cause below issue, so the 0s placeholders for the constructor are always required? Is this expected in PyMTL?

    assert False, f"unrecognized datatype instance {instance}"
E   AssertionError: unrecognized datatype instance [Bits3(0x0), Bits3(0x0), Bits3(0x0), Bits3(0x0)]
E   assert False

Thanks,