More PIIX bugs

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

Been polishing up the new libata driver and found some more apparent
errors in the drivers/ide/pci one.

- Original PIIX is in the PCI table but the driver plays with and
assumes that slave timing registers and control bits are available. On
the PIIX they are not. You have only one timing set and the bits for
seperate slave timing are reserved.

- On pre UDMA chips it writes to the register space that later chips use
for UDMA enable, even though it isn't used for that on the older devices

- On pre ICH chips it writes to the clock selection register even though
it is not actually there.


Alan