ARM64: add GPIO keys to the defconfig

The Juno board, and likely many other boards, likes to use simple
GPIO keys for input events. Enabled this in the default
ARM64 defconfig.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

arch/arm64/configs/defconfig

@@ -94,6 +94,7 @@ CONFIG_SMC91X=y
 CONFIG_SMSC911X=y
 # CONFIG_WLAN is not set
 CONFIG_INPUT_EVDEV=y
+CONFIG_KEYBOARD_GPIO=y
 # CONFIG_SERIO_SERPORT is not set
 CONFIG_SERIO_AMBAKMI=y
 CONFIG_LEGACY_PTY_COUNT=16