of/pci: Add of_pci_dma_range_parser_init() for dma-ranges parsing support

Several host bridge drivers duplicate of_pci_range_parser_init() in order
to parse their dma-ranges property.

Provide of_pci_dma_range_parser_init() for that use case.

Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>