m68knommu: fix gpio warnings for ColdFire 5307 targets

Fix these compiler warnings:

arch/m68knommu/platform/5307/gpio.c:35:3: warning: initialisation makes pointer from integer without a cast
arch/m68knommu/platform/5307/gpio.c:36:3: warning: initialisation makes pointer from integer without a cast
arch/m68knommu/platform/5307/gpio.c:37:3: warning: initialisation makes pointer from integer without a cast

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