libata-acpi: add ATA_FLAG_ACPI_SATA port flag

Whether a controller needs IDE or SATA ACPI hierarchy is determined by
the programming interface of the controller not by whether the
controller is SATA or PATA, or it supports slave device or not.  This
patch adds ATA_FLAG_ACPI_SATA port flags which tells libata-acpi that
the port needs SATA ACPI nodes, and sets the flag for ahci and
sata_sil24.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>