i2c: make i2c_unregister_device() ERR_PTR safe

We are moving towards returning ERR_PTRs when i2c_new_*_device() calls
fail. Make sure its counterpart for unregistering handles ERR_PTRs as
well.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/i2c-core-base.c

@@ -832,7 +832,7 @@ EXPORT_SYMBOL_GPL(i2c_new_device);
  */
 void i2c_unregister_device(struct i2c_client *client)
 {
-	if (!client)
+	if (IS_ERR_OR_NULL(client))
 		return;
 
 	if (client->dev.of_node) {