"ranges" is a standard property and we have common helper functions for
parsing it, so let's use them.
Tested-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/20230206194503.1162108-1-robh@kernel.orgSigned-off-by: Rob Herring <robh@kernel.org>