irqdomain: Introduce is_fwnode_irqchip helper

Since there will be several places checking if fwnode.type
is equal FWNODE_IRQCHIP, this patch adds a convenient function
for this purpose.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index abf2ffa..fcd327f 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -972,7 +972,7 @@
 		return 0;
 	}
 
-	if (fwspec->fwnode->type == FWNODE_IRQCHIP) {
+	if (is_fwnode_irqchip(fwspec->fwnode)) {
 		if(fwspec->param_count != 2)
 			return -EINVAL;