Add therm_adt746x support to PowerPC debian-installer

Precise hw-detect_1.88ubuntu1

This is a continuation of this bug https://bugs.launchpad.net/ubuntu/+source/linux/+bug/923094 that I raised against the kernel. The outcome of that bug report was that therm_adt746x is now built into the PowerPC kernel.
The therm_adt746x module is used to control the fan on G4 iBooks and AlBooks. A lot of the PowerPC testers (myself included) use these machines for testing so it is important that we have this module loaded during the install.

I rather naively pushed for the therm_adt746x module be built into the d-i kernel - not realising that that would in fact mean it is built into the normal kernel too. I'm now looking for a better solution to that since there are a lot of PowerPC machines that don't use therm_adt746x.

I made a mistake in that bug report when I said the code does not exist to modprobe therm_adt746x automatically. It actually does, only it is currently partially commented out in the hw-detect file discover-mac-io.sh:

# drivers/macintosh
 if [ "$name" = fan ]; then
  case $compatible in
      adt7460|adt7467)
   # not in d-i yet
   # echo "therm_adt746x:iBook/AlBook G4 ADT746x thermostat"
   register-module therm_adt746x
   ;;

Is it still possible for Precise 12.04 (I know there have been various feature freezes recently) to uncomment the echo line so that therm_adt746x can be built as a module in the d-i kernel?

Thanks!