regulator: ti-abb: Make use of the helper function devm_ioremap related

Use the devm_platform_ioremap_resource_byname() helper instead of
calling platform_get_resource_byname() and devm_ioremap/devm_ioremap_resource()
separately

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Link: https://lore.kernel.org/r/20210908105745.1984-1-caihuoqing@baidu.com
Signed-off-by: Mark Brown <broonie@kernel.org>