gpiolib: Follow usual pattern for gpiod_remove_lookup_table() call

The usual pattern for the remove calls, like gpiod_remove_lookup_table(),
is to be NULL-aware, i.o.w. become a no-op whenever parameter is NULL.
Update gpiod_remove_lookup_table() call to follow this pattern.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/gpio/gpiolib.c

@@ -3460,6 +3460,10 @@ EXPORT_SYMBOL_GPL(gpiod_add_lookup_table);
  */
 void gpiod_remove_lookup_table(struct gpiod_lookup_table *table)
 {
+	/* Nothing to remove */
+	if (!table)
+		return;
+
 	mutex_lock(&gpio_lookup_lock);
 
 	list_del(&table->list);