Merge ACPI device object management changes for v5.20-rc1.

 - Use the facilities provided by the driver core and some additional
   helpers to handle the children of a given ACPI device object in
   multiple places instead of using the children and node list heads in
   struct acpi_device which is error prone (Rafael Wysocki).

 - Fix ACPI-related device reference counting issue in the hisi_lpc bus
   driver (Yang Yingliang).

 - Drop the children and node list heads that are not needed any more
   from struct acpi_device (Rafael Wysocki).

 - Drop driver member from struct acpi_device (Uwe Kleine-König).

 - Drop redundant check from acpi_device_remove() (Uwe Kleine-König).

* acpi-bus:
  ACPI: bus: Drop unused list heads from struct acpi_device
  hisi_lpc: Use acpi_dev_for_each_child()
  bus: hisi_lpc: fix missing platform_device_put() in hisi_lpc_acpi_probe()
  ACPI: bus: Drop driver member of struct acpi_device
  ACPI: bus: Drop redundant check in acpi_device_remove()
  mfd: core: Use acpi_dev_for_each_child()
  ACPI / MMC: PM: Unify fixing up device power
  soundwire: Use acpi_dev_for_each_child()
  platform/x86/thinkpad_acpi: Use acpi_dev_for_each_child()
  ACPI: scan: Walk ACPI device's children using driver core
  ACPI: bus: Introduce acpi_dev_for_each_child_reverse()
  ACPI: video: Use acpi_dev_for_each_child()
  ACPI: bus: Export acpi_dev_for_each_child() to modules
  ACPI: property: Use acpi_dev_for_each_child() for child lookup
  ACPI: container: Use acpi_dev_for_each_child()
  USB: ACPI: Replace usb_acpi_find_port() with acpi_find_child_by_adr()
  thunderbolt: ACPI: Replace tb_acpi_find_port() with acpi_find_child_by_adr()
  ACPI: glue: Introduce acpi_find_child_by_adr()
  ACPI: glue: Introduce acpi_dev_has_children()
  ACPI: glue: Use acpi_dev_for_each_child()