of/address: Rework of_pci_range parsing for non-PCI buses

The only PCI specific part of of_pci_range_parser_one() is the handling
of the 3rd address cell. Rework it to work on regular 1 and 2 cell
addresses.

Use defines and a union to avoid a treewide renaming of the parsing
helpers and struct.

Signed-off-by: Rob Herring <robh@kernel.org>