gpio: max732x: add error handling for i2c_new_dummy

When i2c_new_dummy fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling i2c_new_dummy.

Signed-off-by: Zhouyang Jia <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-max732x.c

···
 		chip->client_group_a = client;
 		if (nr_port > 8) {
 			c = i2c_new_dummy(client->adapter, addr_b);
+			if (!c) {
+				dev_err(&client->dev,
+					"Failed to allocate I2C device\n");
+				ret = -ENODEV;
+				goto out_failed;
+			}
 			chip->client_group_b = chip->client_dummy = c;
 		}
 		break;
···
 		chip->client_group_b = client;
 		if (nr_port > 8) {
 			c = i2c_new_dummy(client->adapter, addr_a);
+			if (!c) {
+				dev_err(&client->dev,
+					"Failed to allocate I2C device\n");
+				ret = -ENODEV;
+				goto out_failed;
+			}
 			chip->client_group_a = chip->client_dummy = c;
 		}
 		break;