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.

索引モデルが issue の本文から書いたものです。