ata_piix: save, use saved and restore IOCFG

Certain ACPI implementations mess up IOCFG on _STM making libata
detect cable type incorrectly after a suspend/resume cycle.  This
patch makes ata_piix save IOCFG on attach, use the saved value for
things which aren't dynamic and restore it on detach so that the next
driver also gets the BIOS initialized value.

This patch contains the following changes.

* makes ich_pata_cable_detect() use saved_iocfg.

* make piix_iocfg_bit18_quirk() take @host and use saved_iocfg.

* hpriv allocation moved upwards to save iocfg before doing anything
  else.

This fixes bz#11879.  Andreas Mohr reported and diagnosed the problem.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andreas Mohr <andi@lisas.de>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>