gpiolib: remove redundant callback check

gpiolib: remove redundant callback check

The presence of the .get_direction() callback is already checked in
gpiochip_get_direction(). Remove the duplicated check which also returns
the wrong error code to user-space.

Fixes: e623c4303ed1 ("gpiolib: sanitize the return value of gpio_chip::get_direction()")
Reported-by: Michael Walle <mwalle@kernel.org>
Closes: https://lore.kernel.org/all/DFJAFK3DTBOZ.3G2P3A5IH34GF@kernel.org/
Link: https://lore.kernel.org/r/20260109105557.20024-1-bartosz.golaszewski@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>