arm: add hook to initialize machine
arm: add hook to initialize machine

Add a hook to initialize the machine, and a weak implementation that does
nothing in order to make this hook optional.

Signed-off-by: Fabien Parent <2a93cde040adee823a667eed2882d05f12a84573@gmail.com>

iperry/phabos,gregkh/phabos,fabo-corp/phabos,fabo-corp/phabos,gregkh/phabos,mtitinger/phabos,iperry/phabos,mtitinger/phabos