backlight: apple_bl depends on ACPI

apple_bl uses ACPI interfaces (data & code), so it should depend on ACPI.

  drivers/video/backlight/apple_bl.c:142: warning: 'struct acpi_device' declared inside parameter list
  drivers/video/backlight/apple_bl.c:142: warning: its scope is only this definition or declaration, which is probably not what you want
  drivers/video/backlight/apple_bl.c:201: warning: 'struct acpi_device' declared inside parameter list
  drivers/video/backlight/apple_bl.c:215: error: variable 'apple_bl_driver' has initializer but incomplete type
  drivers/video/backlight/apple_bl.c:216: error: unknown field 'name' specified in initializer
  ...
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Matthew Garrett <mjg@redhat.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/backlight/Kconfig

@@ -246,10 +246,10 @@ config BACKLIGHT_MAX8925
 
 config BACKLIGHT_APPLE
        tristate "Apple Backlight Driver"
-       depends on X86
+       depends on X86 && ACPI
        help
          If you have an Intel-based Apple say Y to enable a driver for its
-	 backlight
+	 backlight.
 
 config BACKLIGHT_TOSA
 	tristate "Sharp SL-6000 Backlight Driver"