update pack_gate

as it was updated in https://github.com/torvalds/linux/commit/64b163fab684e3de47aa8db6cc08ae7d2e194373#diff-0af1468d3dc7f373d70011eda7be1592

This function is mentioned in the `Interrupts/linux-interrupts-2.md`

The issue references a specific Linux kernel commit that updated the pack_gate function. Locate the file `Interrupts/linux-interrupts-2.md` in the repository, find where pack_gate is mentioned, and update the documentation to reflect the changes from the linked commit. Verify the update by reviewing the commit diff to understand what changed.

索引モデルが issue の本文から書いたものです。