PCI: xgene: Use pci_parse_request_of_pci_ranges()

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

There's no need to assign the resources to a temporary list first. Just
use bridge->windows directly and remove all the temporary list handling.

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Toan Le <toan@os.amperecomputing.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Andrew Murray <andrew.murray@arm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>