Simplify init._calculate_fan_in_and_fan_out (#53522)
Summary:
This uses the shape of the tensor instead of directly indexing it. This is useful when extending PyTorch's tensor class, e.g. for lazy access. Since the `init` sub-module doesn't check for `torch_function`, it is not possibly to override its functions. Explicitly indexing the tensor will force a call to tensor() and reconstruct the full tensor/explicitly access the elements. Simply using the shape allows to avoid that.
Fixes https://github.com/pytorch/pytorch/issues/53540
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53522
Reviewed By: anjali411
Differential Revision: D26947794
Pulled By: jbschlosser
fbshipit-source-id: 80cd65efed16383f21363cee2eb404c9bc05971c
