km: add Kconfig menus for KM boards

To execute the conversion away from board specific header files, Kconfig
menus have been implemented for all KM boards and additionally for those
having an ARM architecture.

For the moment, the preprocessor definitions stay in the headers. The
boolean types, however, needed a modification (#define CONFIG_* 1).

The default configuration files of some boards required an update in order
to not change the currently defined values of the configurations.

Signed-off-by: Pascal Linder <pascal.linder@edu.hefr.ch>
Signed-off-by: Holger Brunck <holger.brunck@ch.abb.com>
Signed-off-by: Stefan Roese <sr@denx.de>