[ARM] 3140/1: NSLU2 machine support

Patch from Alessandro Zummo

This patch adds support for the LinkSys NSLU2 running with
both big and little-endian kernels. The LinkSys NSLU2 is
a cost engineered ARM, XScale 420 based system similar to
the the Intel IXDP425 evaluation board. It uses the
IXP4XX ARCH.

While this patch applies independently of other patches
the resultant kernel requires further patches to successfully
use onboard devices, including the onboard flash. Since these
patches are independent of this one they will be submitted
separately.

A defconfig is not included here because not all of
the required drivers are actually in the kernel.
We intend to provide one as soon as the patches
will be incorporated in mainstream.

This patch is the combined work of nslu2-linux.org

Signed-off-by: John Bowler <jbowler@acm.org>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>