gpio: uapi: clarify default_values being logical

The documentation for default_values mentions high/low which can be
confusing, particularly when the ACTIVE_LOW flag is set.

Replace high/low with active/inactive to clarify that the values are
logical not physical.

Similarly, clarify the interpretation of values in struct gpiohandle_data.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>