ARM: pxa: remove raumfeld board files and defconfig

These boards are now fully ported to device-tree, so the old implementation
can go away.

The defconfig needs downstream quirks anyway, so we can just remove it from
mainline.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>