gpiolib: probe deferral error reporting

Actually report the error code from devm_regulator_get() which may as
well just be a probe deferral.

This is e.g. what one gets upon booting a Colibri T20:

gpiochip_add_data_with_key: GPIOs 0..223 (tegra-gpio) failed to register

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -1414,9 +1414,9 @@ err_free_descs:
 err_free_gdev:
 	ida_simple_remove(&gpio_ida, gdev->id);
 	/* failures here can mean systems won't boot... */
-	pr_err("%s: GPIOs %d..%d (%s) failed to register\n", __func__,
+	pr_err("%s: GPIOs %d..%d (%s) failed to register, %d\n", __func__,
 	       gdev->base, gdev->base + gdev->ngpio - 1,
-	       chip->label ? : "generic");
+	       chip->label ? : "generic", status);
 	kfree(gdev);
 	return status;
 }