powerpc/km: remove unmaintained board KMLION1

This board is unmaintained and can be removed. This also allows us to
remove kmp204x-common.h and integrate it in kmp204x.h.

Signed-off-by: Valentin Longchamp <valentin.longchamp@ch.abb.com>
Signed-off-by: Holger Brunck <holger.brunck@ch.abb.com>
Signed-off-by: Stefan Roese <sr@denx.de>