genirq/irqdomain: Remove redundant NULL pointer check on fwnode

The is_fwnode_irqchip() helper will check if the fwnode_handle is empty.
There is no need to perform a redundant check outside of it.
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200716083905.287-1-yuzenghui@huawei.com

kernel/irq/irqdomain.c

@@ -142,7 +142,7 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size,
 	if (!domain)
 		return NULL;
 
-	if (fwnode && is_fwnode_irqchip(fwnode)) {
+	if (is_fwnode_irqchip(fwnode)) {
 		fwid = container_of(fwnode, struct irqchip_fwid, fwnode);
 
 		switch (fwid->type) {