[ARM] pxa/colibri270: Split module and base board code

Follow the idea of several MX31 based boards and split code that is
related to the module from code that is baseboard specific. This makes
adding new base board support easier, while avoiding code duplication.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>