gpio: mxs: implement get_direction callback
gpio: mxs: implement get_direction callback

gpiolib's gpiod_get_direction() function returns the EINVAL error
if .get_direction callback is not defined.
The patch implements the callback for mxs chip which is useful
for debugging.

Inspired by arch/arm/mach-at91/gpio.c

On the moment the patch is required to get the patch
"serial: mxs-auart: enable PPS support" working.
It is planned to introduce new mctrl_gpio helpers to avoid
gpiod_get_direction() function.

Signed-off-by: Janusz Uzycki <d03a03bee1a0590d1da68111966be566583bb18c@elproma.com.pl>
Acked-by: Alexandre Courbot <301cd6a3ea50a894b4b51e385c5eb12b9a4ffc0c@nvidia.com>
Signed-off-by: Linus Walleij <9cd9d802d23c0ed5e224beabf4ae4a5c478746ef@linaro.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs