[POWERPC] Add an optional device_node pointer to the irq_host

The majority of irq_host implementations (3 out of 4) are associated
with a device_node, and need to stash it somewhere. Rather than having
it somewhere different for each host, add an optional device_node pointer
to the irq_host structure.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 74c64c0..25a81f7 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -271,7 +271,7 @@
 {
 	rb->dbase = mpic->dcr_base;
 	rb->doff = offset;
-	rb->dhost = dcr_map(mpic->of_node, rb->dbase + rb->doff, size);
+	rb->dhost = dcr_map(mpic->irqhost->of_node, rb->dbase + rb->doff, size);
 	BUG_ON(!DCR_MAP_OK(rb->dhost));
 }
 
@@ -861,10 +861,8 @@
 
 static int mpic_host_match(struct irq_host *h, struct device_node *node)
 {
-	struct mpic *mpic = h->host_data;
-
 	/* Exact match, unless mpic node is NULL */
-	return mpic->of_node == NULL || mpic->of_node == node;
+	return h->of_node == NULL || h->of_node == node;
 }
 
 static int mpic_host_map(struct irq_host *h, unsigned int virq,
@@ -985,10 +983,9 @@
 	
 	memset(mpic, 0, sizeof(struct mpic));
 	mpic->name = name;
-	mpic->of_node = of_node_get(node);
 
-	mpic->irqhost = irq_alloc_host(IRQ_HOST_MAP_LINEAR, isu_size,
-				       &mpic_host_ops,
+	mpic->irqhost = irq_alloc_host(of_node_get(node), IRQ_HOST_MAP_LINEAR,
+				       isu_size, &mpic_host_ops,
 				       flags & MPIC_LARGE_VECTORS ? 2048 : 256);
 	if (mpic->irqhost == NULL) {
 		of_node_put(node);