[bugfix][relay] fix wrong calculate logic about celu

[jikechao]

The calculation formula of CELU is wrong in relay/pytorch. This pr fix it.

From the pytorch documentation, we can get the calculating logic of CELU.

Reproducible Script

import torch
from tvm import relay
import tvm
import numpy as np

m = torch.nn.CELU()
input_data = torch.tensor([[-1.0, 2.0]], dtype=torch.float32)

torch_outputs = m(input_data)

trace = torch.jit.trace(m, input_data)
input_shapes = [('input0', torch.Size([1,2]))]

mod, params = relay.frontend.from_pytorch(trace, input_shapes)

with tvm.transform.PassContext(opt_level=3):
    exe = relay.create_executor('graph', mod=mod, params=params, device=tvm.device('llvm', 0), target='llvm').evaluate()
input_tvm = {'input0': np.array([[-1.,  2.]], dtype='float32')}
tvm_outputs = exe(**input_tvm).asnumpy()

np.testing.assert_allclose(torch_outputs, tvm_outputs, rtol=1e-3, atol=1e-3)

script output

cc @AndrewZhaoLuo @echuraev

[tvm-bot]

Thanks for contributing to TVM! Please refer to the contributing guidelines https://tvm.apache.org/docs/contribute/ for useful information and tips. Please request code reviews from Reviewers by @-ing them in a comment.

• cc @shingjan _{See #10317 for details}

_{Generated by tvm-bot}

[echuraev]

LGTM. Thank you for your PR!