PCI: dwc: Use pci_parse_request_of_pci_ranges()

Convert the Designware host bridge to use the common
pci_parse_request_of_pci_ranges().

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Jingoo Han <jingoohan1@gmail.com>
Cc: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Andrew Murray <andrew.murray@arm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>