LVBS: Use VP index and separate CPU entry points

[sangho2]

This PR make LVBS use VP index instead of CPUID-based APIC ID and
separate CPU entry points for BSP and APs.

[github-actions]

🤖 SemverChecks 🤖 ⚠️ Potential breaking API changes detected ⚠️

Click for details

--- failure function_missing: pub fn removed or renamed ---

Description:
A publicly-visible function cannot be imported by its prior path. A `pub use` may have been removed, or the function itself may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.46.0/src/lints/function_missing.ron

Failed in:
  function litebox_platform_lvbs::arch::get_core_id, previously in file /home/runner/work/litebox/litebox/target/semver-checks/git-main/c39d3556b2aebc020466a3ec879a05a86a3c0848/litebox_platform_lvbs/src/arch/x86/mod.rs:24

[sangho2]

Issue #677