arm: mvebu: Move some defines to common include file

This patch moves some config options to the mvebu common include file.
Making it easier to not forget these defines for new boards.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Luka Perkov <luka.perkov@sartura.hr>
Cc: Dirk Eibach <dirk.eibach@gdsys.cc>