feat: Add .code64 directive to naked assembly for VMX entry and exit

[ZR233]

axplat中 .code32 代码可能影响到了后续代码，编译时产生

error: register %r15 is only available in 64-bit mode
    |
note: instantiated into assembly here
   --> <inline asm>:467:13
    |
467 |         pop r15
    |             ^^^

依赖版本问题，需要先通过：
arceos-hypervisor/axdevice_base#40
arceos-hypervisor/x86_vlapic#6

[Copilot]

Pull Request Overview

This PR addresses a compilation error related to assembly code generation by adding .code64 directives to naked assembly blocks in VMX entry and exit functions. The error occurred because .code32 directives elsewhere in the codebase were affecting subsequent code compilation, causing the assembler to reject 64-bit register usage.

• Added .code64 directive to VMX entry macro to ensure 64-bit mode assembly
• Added .code64 directive to VMX exit function to ensure 64-bit mode assembly

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