Bias Gelu Fusion + GEGLU errors

[sdtblck]

Describe the bug
the bias gelu fusion is expecting a tensor, but we pass it an int if bias is None. Should just be able to pass it a zeros tensor to fix.

 File "/nobackup/users/andonian/gpt-neox/megatron/model/transformer.py", line 117, in forward
    bias_gelu_impl(gate, bias_2)
  File "/nobackup/users/andonian/gpt-neox/megatron/model/fused_bias_gelu.py", line 52, in forward
    return bias_gelu(bias, input)
RuntimeError: bias_gelu() Expected a value of type 'Tensor (inferred)' for argument 'bias' but instead found type 'int'.
Inferred 'bias' to be of type 'Tensor' because it was not annotated with an explicit type.
Position: 0
Value: 0
Declaration: bias_gelu(Tensor bias, Tensor y) -> (Tensor)
Cast error details: Unable to cast Python instance to C++ type (compile in debug mode for details)