Patch from Lennert Buytenhek

The ixp2000 gpio cleanup broke the ixdp2800 build as it moved some
gpio-related functions from arch/platform.h to arch/gpio.h and the
ixdp2x00 support code used those functions but didn't include the
latter header file.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>