staging: greybus: remove unnecessary GPIO line direction check

As of commit 92ac7de3 ("gpiolib: don't allow setting values on input
lines"), the GPIO core makes sure values cannot be set on input lines.
Remove the unnecessary check.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Rui Miguel Silva <rui.silva@linaro.org>
Link: https://lore.kernel.org/r/20250610152036.86099-1-brgl@bgdev.pl


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>