machintosh: select defaults for cooling

I have this pretty nasty problem when trying to boot up a fresh
openSuSE DVD on a PowerMac G5: the kernel by default does not have
CONFIG_WINDFARM_PM72 enabled, with the effect that the cooling
is not functioning.

The BIOS on the PowerMac G5 reacts to this by, after a grace
period when the BIOS has waited for the OS to take over, increasing
the fan speeds so it sounds like an airplane is in the room, and
after another grace period simply cutting the power to the
machine. This is done not beacuse the cooling is not working, but
because the BIOS is not recieving handover of cooling from the
OS, so it panics and give up. The problem has been reported by
Linux users online.

Needless to say, this makes it impossible to install the OS
before the machine turns itself off.

The g5_defconfig looks like this:
CONFIG_PMAC_SMU=y
CONFIG_WINDFARM=y
CONFIG_WINDFARM_PM81=y
CONFIG_WINDFARM_PM91=y
CONFIG_WINDFARM_PM112=y
CONFIG_WINDFARM_PM121=y

Notably PM72 is missing, making the PowerMac G5 fail.

The defconfig is not the right place to do this: it should be
done by default when selecting Mac support for PPC/PPC64 and
especially for the Macs CPUfreq driver. We select SMU by default
for PPC_PMAC64, WINDFARM by default on PPC_PMAC and all the
WINDFARM thermal managers by default if CPU_FREQ_PMAC64 is
selected.

I think this will make install images "just work" in the G5
Macs, with openSuSE and others.

Cc: stable@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>