powerpc: fsl_soc: Use of_range_to_resource() for "ranges" parsing

"ranges" is a standard property with common parsing functions. Users
shouldn't be implementing their own parsing of it. Refactor the FSL RapidIO
"ranges" parsing to use of_range_to_resource() instead.

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230609183238.1767186-1-robh@kernel.org