ata: libata-core: Fix ata_pci_shutdown_one()

This reverts commit 5b6fba54.

Commit 5b6fba54 ("ata: libata-core: Detach a port devices on
shutdown") modified the function ata_pci_shutdown_one() to stop
(suspend) devices attached to the ports of a PCI AHCI adapter to ensure
that drives are spun down before shutting down a system. However, this
is done only for PCI adapters and not for other types of adapters. This
limitation was addressed with commit 24eca2dc ("scsi: sd: Introduce
manage_shutdown device flag"). With this, all ATA disks are spun down on
system shutdown, which make the changes introduced with 5b6fba54
useless.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>