Only scan one device if it's a PCIe downstream port.
A PCIe downstream port normally leads to a link with only device 0 on
it. As an optimization, scan only for device 0 in that case.
Signed-off-by: Jianjun Wang <jianjun.wang@mediatek.com>
Change-Id: Id184d03b33e1742b18efb3f11aa9b2f81fa03806
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56788
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
777ffff442