bus: hisi_lpc: Use devm_platform_ioremap_resource

The struct resource is not used for anything else, so we can simplify
the code a bit by using the helper function.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>