[POWERPC] Move of_irq_to_resource from prom.h to prom_parse.c

In the powerpc architecture, of_irq_to_resource, currently sitting in
prom.h, needs irq_of_parse_and_map and NO_IRQ from asm-powerpc/irq.h.
The solution suggested by Benjamin Herrenschmidt is to move it to
arch/powerpc/kernel/prom_parse.c.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/prom_parse.c b/arch/powerpc/kernel/prom_parse.c
index aa40a53..78ee8d5 100644
--- a/arch/powerpc/kernel/prom_parse.c
+++ b/arch/powerpc/kernel/prom_parse.c
@@ -1042,3 +1042,17 @@
 }
 EXPORT_SYMBOL(of_get_mac_address);
 
+int of_irq_to_resource(struct device_node *dev, int index, struct resource *r)
+{
+	int irq = irq_of_parse_and_map(dev, index);
+
+	/* Only dereference the resource if both the
+	 * resource and the irq are valid. */
+	if (r && irq != NO_IRQ) {
+		r->start = r->end = irq;
+		r->flags = IORESOURCE_IRQ;
+	}
+
+	return irq;
+}
+EXPORT_SYMBOL_GPL(of_irq_to_resource);