Opinfo test for mvlgamma: add epsilon (#71794)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71794
mvlgamma(inp, p) requires that all the elements of inp are > (p-1)/2.
The opinfo test was occasionally producing inputs with elements == (p-1/2), which would generate errors like:
```
ERROR: test_nnc_correctness_mvlgamma_mvlgamma_p_5_cpu_bfloat16 (__main__.TestNNCOpInfoCPU)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/path/pytorch/torch/testing/_internal/common_device_type.py", line 381, in instantiated_test
raise rte
File "/path/pytorch/torch/testing/_internal/common_device_type.py", line 376, in instantiated_test
result = test(self, **param_kwargs)
File "/path/pytorch/torch/testing/_internal/common_device_type.py", line 753, in test_wrapper
return test(*args, **kwargs)
File "/path/pytorch/torch/testing/_internal/common_device_type.py", line 907, in only_fn
return fn(slf, *args, **kwargs)
File "/path/pytorch/test/test_jit_fuser_te.py", line 2293, in test_nnc_correctness
ref = variant(*clone_inputs((sample.input, *sample.args)), **sample.kwargs)
RuntimeError: All elements must be greater than (p-1)/2
```
repro example: https://gist.github.com/davidberard98/9da688e31cdfbaed7e990746b28a4ba2
Test Plan: Imported from OSS
Reviewed By: qihqi
Differential Revision: D33780905
Pulled By: davidberard98
fbshipit-source-id: c9afd443bc90ce68f33b97498921b447e4f7d1d8
(cherry picked from commit a974b03f071d1bebf90a33edf801a5d6365b91b2)
