[PATCH] macintosh/adbhid.c: adb buttons support for aluminium PowerBook G4

This patch adds support for the special adb buttons of the aluminium
PowerBook G4.

Signed-off-by: Andreas Jaggi <andreas.jaggi@waterwave.ch>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>