PCI: mediatek: Add controller support for MT7629

MT7629 is an ARM platform SoC which has the same PCIe IP as MT7622.

The HW default value of its PCI host controller Device ID is invalid,
fix it to match the hardware implementation.

Signed-off-by: Jianjun Wang <jianjun.wang@mediatek.com>
[lorenzo.pieralisi@arm.com: commit log/minor spelling update]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Acked-by: Ryder Lee <ryder.lee@mediatek.com>