system.formfactor never set for PMU

[Richard Hughes]

David,

For PowerMac based machines, system.formfactor is never set to anything
other than "unknown".
GNOME Power Manager has to know what type of machine we are to switch on
the power-saving calls, as discussed previously.

Patch attached that sets this if we have a battery bay, as suggested by
Matthew Garrett.

ChangeLog:

hald/linux2/pmu.c (pmu_synthesize_hotplug_events): Set the key
system.formfactor to "laptop" if we have a battery bay.

Okay to commit?

Richard.