powerpc: Fix irq_alloc_host() reference counting and callers

When I changed irq_alloc_host() to take an of_node
(52964f87c64e6c6ea671b5bf3030fb1494090a48: "Add an optional
device_node pointer to the irq_host"), I botched the reference
counting semantics.

Stephen pointed out that it's irq_alloc_host()'s business if
it needs to take an additional reference to the device_node,
the caller shouldn't need to care.

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 a281341..5788a6a 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -1016,13 +1016,11 @@
 	memset(mpic, 0, sizeof(struct mpic));
 	mpic->name = name;
 
-	mpic->irqhost = irq_alloc_host(of_node_get(node), IRQ_HOST_MAP_LINEAR,
+	mpic->irqhost = irq_alloc_host(node, IRQ_HOST_MAP_LINEAR,
 				       isu_size, &mpic_host_ops,
 				       flags & MPIC_LARGE_VECTORS ? 2048 : 256);
-	if (mpic->irqhost == NULL) {
-		of_node_put(node);
+	if (mpic->irqhost == NULL)
 		return NULL;
-	}
 
 	mpic->irqhost->host_data = mpic;
 	mpic->hc_irq = mpic_irq_chip;