Generalize acpi_pci_save_handle and preliminary ATA ACPI support.

[Takanori Watanabe]

I wrote preliminary support of ACPI support for PCI ATA device.
Currently it does nothing but recognize acpi handle.
To use some support function in PCI, I generalized acpi_pci_save_handle
and export it as acpi device method.

To support ATA channel it seems that it require some modification to
ATA driver. 

ACPI has some ATA support. for more information, Section 9.9 of
ACPI 3.0 specification.

Regards.

#text/plain /home/takawata/acpibusdiff
#text/plain /home/takawata/ata-pci-acpi.c