[PATCH v2] Add the i.MX23 architecure to barebox

[Juergen Beisert]

This patch adds the basic support for the i.MX23 architecture. This
CPUs is branded with i.MX, but they are mostly of type STMP378X from SigmaTel.
So, it does not share most of its internal devices with the other i.MX CPUs.
That's why I open a new sub architecture 'mach-stm'.

This is v2 of my patch series to add the i.MX23 architecture. Slightly
modified for easier i.MX28 addition later on. Defconfigs are regenerated.

jbe