tools: gpioget: add new --dir-as-is option for GPO read-back

tools: gpioget: add new --dir-as-is option for GPO read-back

Both legacy sysfs and new character device API support querying line
state of a GPIO configured as output. But while sysfs /value can
be read for these output GPIOs, gpioget unconditionally muxes the
line as input. To ease migration to the new user API, add a new
--dir-as-is parameter that doesn't force the line to input.

This is especially useful for GPIO controllers that maintain their
last configured output state.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>