PCI: Export pci_parse_request_of_pci_ranges()

pci_parse_request_of_pci_ranges() is missing a module export, so add it.

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