gpioinfo_*() assume their gpio_info pointer parameter to be valid and
don't ensure the gpio to be requested.

This drops several checks for being requested and allows further
extensions to work with unrequested gpios.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>