config: enable gpiolib & sysfs like other sun defconfigs
config: enable leds class like other sun defconfigs
config: enable ext4 sec like other sun defconfigs
cubieboard: minimalize config with savedefconfig

  cp arch/arm/configs/cubieboard_defconfig ./.config
  make ARCH=arm savedefconfig
  cp defconfig arch/arm/configs/cubieboard_defconfig

To stay in sync with other sunxi defconfigs