power: reset: rmobile-reset: Use devm_platform_ioremap_resource() helper

Use device life-cycle managed ioremap function to simplify probe and
exit paths.

Signed-off-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20240212162831.67838-10-afd@ti.com


Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>