gfsc100: Enable GPIO_SYSFS

Provide userspace access to the GPIOs to allow the reset_tuner script to
reset the USB bridge.

Google-Bug-Id: 25378377

Change-Id: I251f9566ce3087394c7f817be1c85d48d153e9ff
diff --git a/arch/arm/configs/gfsc100_defconfig b/arch/arm/configs/gfsc100_defconfig
index 1461338..eaef5c1 100644
--- a/arch/arm/configs/gfsc100_defconfig
+++ b/arch/arm/configs/gfsc100_defconfig
@@ -226,6 +226,7 @@
 CONFIG_SPI=y
 CONFIG_SPI_DEBUG=y
 # CONFIG_SPI_MSPD_LOW_SPEED is not set
+CONFIG_GPIO_SYSFS=y
 CONFIG_HWMON_DEBUG_CHIP=y
 CONFIG_SENSORS_LM63=y
 CONFIG_WATCHDOG=y