pinctrl: iproc-gpio: Silence probe deferral messages

We can have gpiochip_add_data() return -EPROBE_DEFER which will make us
produce the "unable to add GPIO chip" message which is confusing. Use
dev_err_probe() to silence probe deferral messages.

Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Link: https://lore.kernel.org/r/20230808180733.2081353-2-florian.fainelli@broadcom.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>