Support the operation of generic pinconf. The supported config arguments
are INPUT_SCHMITT, INPUT_SCHMITT_ENABLE, DRIVE_STRENGHT, BIAS_DISABLE,
BIAS_PULLUP, BIAS_PULLDOWN, SLEW_RATE.
Signed-off-by: NHaojian Zhuang <haojian.zhuang@linaro.org>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>