ARM: pxa: Toradex Colibri PXA270 CF support

This driver also contains structures to eventually support PXA320. This is
planned to be added in a later patch.

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