PCI: mediatek: Use devm_of_pci_get_host_bridge_resources() to parse DT

Use the devm_of_pci_get_host_bridge_resources() API in place of the PCI OF
DT parser.

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>