Implement PIO-mode IDE driver that scans primary and secondary channels
for ATA hard drives and ATAPI CD/DVD drives using IDENTIFY commands.
Features:
- Scans 4 possible devices (2 channels x 2 drives each)
- ATA IDENTIFY DEVICE for hard drives
- ATAPI IDENTIFY PACKET DEVICE for CD/DVD drives
- PIO-mode 28-bit LBA sector read/write for ATA drives
- Model string extraction and sector count parsing
- Registers as kernel driver via REGISTER_DRIVER macro
- Registers devices with devicefs: ATA → hdd class, ATAPI → cd class
- Added inw/outw to port_io.h for 16-bit I/O
Tested: QEMU detects hdd1 (QEMU HARDDISK) and cd1 (QEMU DVD-ROM).
