Wrong port number used when disable i8259 PIC

https://github.com/equation314/RVM-Tutorial/blob/7687541241aa80db65e8043b50cfa0593bfcfb84/hypervisor/src/arch/x86_64/lapic.rs#L22-L26

Should be

```rust
Port::::new(0x21).write(0xff);
Port::::new(0xA1).write(0xff);
```

Open hypervisor/src/arch/x86_64/lapic.rs at lines 22-26 and compare the port writes with the issue's expected values. Confirm the PIC-disable code uses ports 0x21 and 0xA1; the issue provides no test file, so completion is verified by the corrected lines and the project's available checks.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.