of/irq: Export of_irq_find_parent again

of_irq_find_parent was made static since it had no users outside of
of_irq.c. Export it again since we are going to use it again.

Signed-off-by: Carlo Caione <carlo@endlessm.com>
[robh: move of_irq_find_parent to correct ifdef section]
Signed-off-by: Rob Herring <robh@kernel.org>
diff --git a/include/linux/of_irq.h b/include/linux/of_irq.h
index 039f2ee..f648acf 100644
--- a/include/linux/of_irq.h
+++ b/include/linux/of_irq.h
@@ -46,6 +46,7 @@
 extern int of_irq_get_byname(struct device_node *dev, const char *name);
 extern int of_irq_to_resource_table(struct device_node *dev,
 		struct resource *res, int nr_irqs);
+extern struct device_node *of_irq_find_parent(struct device_node *child);
 extern struct irq_domain *of_msi_get_domain(struct device *dev,
 					    struct device_node *np,
 					    enum irq_domain_bus_token token);
@@ -70,6 +71,11 @@
 {
 	return 0;
 }
+static inline void *of_irq_find_parent(struct device_node *child)
+{
+	return NULL;
+}
+
 static inline struct irq_domain *of_msi_get_domain(struct device *dev,
 						   struct device_node *np,
 						   enum irq_domain_bus_token token)