ARM: imx_v4_v5_defconfig: Add CONFIG_GPIO_SYSFS

Add CONFIG_GPIO_SYSFS as it is helpful for accessing GPIO from userspace.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>