bus: hisi_lpc: Don't dereference fwnode handle

Use dev_fwnode() and acpi_fwnode_handle() instead of dereferencing
an fwnode handle directly, which is a better coding practice.

While at it, reuse fwnode instead of ACPI_COMPANION().

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>