[ARM] 3618/1: add defconfig for logicpd pxa270 card engine

Patch from Lennert Buytenhek

As it's slightly nontrivial to make it possible to build a single
kernel image for both the mainstone and the logicpd pxa270 card engine,
add a separate defconfig for the logicpd pxa270 card engine for now.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>