ARM: ixp4xx: drop duplicate header gpio.h

Drop duplicate header gpio.h from dsmg600-setup.c.
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>

arch/arm/mach-ixp4xx/dsmg600-setup.c

@@ -26,7 +26,6 @@
 #include <linux/reboot.h>
 #include <linux/i2c.h>
 #include <linux/i2c-gpio.h>
-#include <linux/gpio.h>
 
 #include <mach/hardware.h>