mv: seperate kirkwood and armada from common setting

Since there are lots of difference between kirkwood and armada series,
it is better to seperate them but still keep the most common file
shared by all marvell platform in the mv-common configure file.

This patch move the kirkwood only driver definitoin in mv-common to
the <soc_name>/config.h.

This patch is tested with compilation for armada100 and guruplug.

Signed-off-by: Lei Wen <leiwen@marvell.com>