of/address: use range parser for of_dma_get_range

of_dma_get_range() does the same ranges parsing as
of_pci_range_parser_one(), so let's refactor of_dma_get_range() to use
it instead.

This commit is no functional change. Subsequent commits will parse more
than the 1st dma-ranges entry.

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