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/cpm1.c b/arch/powerpc/sysdev/cpm1.c
index 58292a0..661df42 100644
--- a/arch/powerpc/sysdev/cpm1.c
+++ b/arch/powerpc/sysdev/cpm1.c
@@ -159,7 +159,7 @@
 
 	out_be32(&cpic_reg->cpic_cimr, 0);
 
-	cpm_pic_host = irq_alloc_host(of_node_get(np), IRQ_HOST_MAP_LINEAR,
+	cpm_pic_host = irq_alloc_host(np, IRQ_HOST_MAP_LINEAR,
 				      64, &cpm_pic_host_ops, 64);
 	if (cpm_pic_host == NULL) {
 		printk(KERN_ERR "CPM2 PIC: failed to allocate irq host!\n");