wrong flags in /proc/pmu/info if on AC without battery

[Sylvain Joyeux <sylvain.joyeux@m4x.org>]

If I remove the battery on my iBook and put it on AC, /proc/pmu/info says

PMU driver version     : 2
PMU firmware version   : 0c
AC Power               : 0
Battery count          : 1

which screws scripts like laptop_mode

cpuinfo:
processor       : 0
cpu             : 7455, altivec supported
clock           : 606.000000MHz
revision        : 0.3 (pvr 8001 0303)
bogomips        : 36.73
timebase        : 18432000
platform        : PowerMac
machine         : PowerBook6,3
motherboard     : PowerBook6,3 MacRISC3 Power Macintosh
detected as     : 287 (iBook G4)
pmac flags      : 0000001b
L2 cache        : 256K unified
pmac-generation : NewWorld
-- 
Sylvain