drivers/macintosh: Various cleanups

This contains the following cleanups:
- make the following needlessly global code static:
  - adb.c: adb_controller
  - adb.c: adb_init()
  - adbhid.c: adb_to_linux_keycodes[]  (also make it const)
  - via-pmu68k.c: backlight_level
  - via-pmu68k.c: backlight_enabled
- remove the following unused code:
  - via-pmu68k.c: sleep_notifier_list

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>