pinctrl/rockchip: Make use of the devm_platform_get_and_ioremap_resource()

Use the devm_platform_get_and_ioremap_resource() helper instead of
calling platform_get_resource() and devm_ioremap_resource()
separately.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>