Some pins like i2c SCL/SDA need the schmitt input function
to avoid crosstalk problems.
Signed-off-by: NAndy Yan <andy.yan@rock-chips.com>
Reviewed-by: NHeiko Stuebner <heiko@sntech.de>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>