[POWERPC] Make sure to of_node_get() the result of pci_device_to_OF_node()

pci_device_to_OF_node() returns the device node attached to a PCI device,
but doesn't actually grab a reference - we need to do it ourselves.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/cell/axon_msi.c

@@ -125,7 +125,7 @@ static struct axon_msic *find_msi_translator(struct pci_dev *dev)
 	const phandle *ph;
 	struct axon_msic *msic = NULL;
 
-	dn = pci_device_to_OF_node(dev);
+	dn = of_node_get(pci_device_to_OF_node(dev));
 	if (!dn) {
 		dev_dbg(&dev->dev, "axon_msi: no pci_dn found\n");
 		return NULL;
@@ -182,7 +182,7 @@ static int setup_msi_msg_address(struct pci_dev *dev, struct msi_msg *msg)
 	int len;
 	const u32 *prop;
 
-	dn = pci_device_to_OF_node(dev);
+	dn = of_node_get(pci_device_to_OF_node(dev));
 	if (!dn) {
 		dev_dbg(&dev->dev, "axon_msi: no pci_dn found\n");
 		return -ENODEV;