memory: renesas-rpc-if: Add wrapper functions

memory: renesas-rpc-if: Add wrapper functions

Even though XSPI and RPCIF has different register layout, reuse the code
by adding wrapper functions to support both XSPI and RPC-IF.

While at it, replace error check for pm_runtime_resume_and_get().

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20250424090000.136804-6-biju.das.jz@bp.renesas.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>