gpiolib: do not print err message for EPROBE_DEFER

The gpiochip may have dependencies from pinmux and so got deferred. Now it
will print error message every time -EPROBE_DEFER is returned which is
unnecessary:

"gpiochip_add_data_with_key: GPIOs 0..31 (gpio-0-31) failed to register, -517"

Hence, do suppress error message for -EPROBE_DEFER case.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>