[DRIVER] pca953x: support reset-gpios shared line

Some systems connect several devices to a single reset GPIO.
For these devices to get out of reset and probe successfully, treat
the reset returning -EBUSY as the line already having been hogged
and do not abort the probe.

drivers/gpio/gpio-pca953x.c

@@ -981,8 +981,15 @@ static int pca953x_probe(struct i2c_client *client,
 		 */
 		reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
 						     GPIOD_OUT_LOW);
-		if (IS_ERR(reset_gpio))
-			return PTR_ERR(reset_gpio);
+		if (IS_ERR(reset_gpio)) {
+			ret = PTR_ERR(reset_gpio);
+			/* reset may be shared with other devices: do not abort on -EBUSY */
+			if (ret != -EBUSY) {
+				dev_err(dev, "Could not get reset-gpios: %d\n", ret);
+				return ret;
+			}
+			dev_warn(dev, "Could not get reset-gpios: already in use\n", ret);
+		}
 	}
 
 	chip->client = client;