Merge branches 'acpi-video', 'acpi-misc' and 'acpi-docs'

Merge ACPI backlight driver changes, miscellaneous ACPI-related changes
and ACPI-related documentation updates for 6.3-rc1:

 - Fix Lenovo Ideapad Z570 DMI match in the ACPI backlight driver (Hans
   de Goede).

 - Silence missing prototype warnings in some places in the ACPI-related
   code (Ammar Faizi).

 - Make kobj_type structures used in the ACPI code constant (Thomas
   Weißschuh).

 - Correct spelling in firmware-guide/ACPI (Randy Dunlap).

 - Clarify the meaning of Explicit and Implicit in the _DSD GPIO
   properties documentation (Andy Shevchenko).

* acpi-video:
  ACPI: video: Fix Lenovo Ideapad Z570 DMI match

* acpi-misc:
  ACPI: make kobj_type structures constant
  ACPI: Silence missing prototype warnings

* acpi-docs:
  Documentation: firmware-guide: gpio-properties: Clarify Explicit and Implicit
  Documentation: firmware-guide/ACPI: correct spelling