m68knommu: fix gpio warnings for ColdFire 520x targets

Fix these compiler warnings:

rch/m68knommu/platform/520x/gpio.c:35:3: warning: initialisation makes pointer from integer without a cast
arch/m68knommu/platform/520x/gpio.c:36:3: warning: initialisation makes pointer from integer without a cast
arch/m68knommu/platform/520x/gpio.c:37:3: warning: initialisation makes pointer from integer without a cast
arch/m68knommu/platform/520x/gpio.c:51:3: warning: initialisation makes pointer from integer without a cast
arch/m68knommu/platform/520x/gpio.c:52:3: warning: initialisation makes pointer from integer without a cast
...

Signed-off-by: Greg Ungerer <gerg@uclinux.org>