ARM: dts: mediatek: Update MT7629 PCIe node for new format

To match the new dts binding. Remove "subsys",unused
interrupt and slot node.Add "interrupt-names",
"linux,pci-domain" and pciecfg node.

Signed-off-by: Chuanjia Liu <chuanjia.liu@mediatek.com>
Acked-by: Ryder Lee <ryder.lee@mediatek.com>
Link: https://lore.kernel.org/r/20210823032800.1660-7-chuanjia.liu@mediatek.com


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>