[FX] Fix python code generation for wrapped getattr() with default value (#64271)

[FX] Fix python code generation for wrapped getattr() with default value (#64271)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64271

Closes #60417

Modified emit_node() in fx/graph.py to generate getattr() call with default value when len(node.args) != 2 instead of accessing the attribute.
Added test_torch_fx_getattr() in test/test_fx.py.

Test Plan:
pytest test/test_fx.py

Imported from OSS

Reviewed By: jamesr66a

Differential Revision: D30671265

fbshipit-source-id: f2db9ea47e0cb247547e200684f715aab006c374