Add CONFIG_GPIO_SYSFS as it is helpful for accessing GPIO from userspace.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>