PCI: mediatek: Set up vendor ID and class type for MT7622

MT7622's hardware default value of vendor ID and class type is not correct,
fix that by setup the correct values before linkup with Endpoint.

Signed-off-by: Honghui Zhang <honghui.zhang@mediatek.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Ryder Lee <ryder.lee@mediatek.com>