[inductor] fix bandwidth extimation for StarDep (#120266)
A lot of HF models fail when inductor_config.bechmark_kernel is enabled. The reason is the bandwidth estimation code assumes every dependencies has an index but StarDep does not. An exception is raised when StarDep.index is being accessed.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/120266
Approved by: https://github.com/eellison, https://github.com/jansel
