Use PCI bus scan to find all ATA controllers. Several IDE fixes.

Use PCI bus scan to find all ATA controllers.  Several IDE fixes.

Find all ATA controllers via a pci bus - don't poke random IO ports.
Force IDE drives to 512 byte sector size; word 5 in identify command
    isn't defined on recent drives.
Add debugging info for extended_access and int 1348 calls.
int 1348 enhancements - general cleanup, report drives as PCI, correct
    iface_path/device_path settings, checksums should be a 2's
    complement, call disk_ret() on all return paths, always use dpte
    revision 0x11, don't set size above 30 bytes.