[PATCH] ppc64: AC Power handling broken for desktops

Currently, AC Power is 0 on a desktop G4.  No batteries present should mean
AC Power == 1.

Signed-off-by: Olaf Hering <olh@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>