reset: ath79: Use devm_platform_ioremap_resource()

Convert platform_get_resource(), devm_ioremap_resource() to a single
call to Use devm_platform_ioremap_resource(), as this is exactly
what this function does.

Suggested-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Ye Xingchen <ye.xingchen@zte.com.cn>
Link: https://lore.kernel.org/r/202302161049100728015@zte.com.cn


Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>