[POWERPC] Avoid possible extra of_node_put in axon_msi.c

I got this warning from gcc:
arch/powerpc/platforms/cell/axon_msi.c:118: warning: 'tmp' may be used uninitialized in this function

Which turns out to be a false positive, but pointed out that it was
possible for the error path in find_msi_translator() to do an extra
of_node_put on a node.  This fixes it by localising the ref counting
a bit.  As a side effect, the warning goes away.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/cell/axon_msi.c

@@ -137,6 +137,7 @@ static struct axon_msic *find_msi_translator(struct pci_dev *dev)
 
 	tmp = dn;
 	dn = of_find_node_by_phandle(*ph);
+	of_node_put(tmp);
 	if (!dn) {
 		dev_dbg(&dev->dev,
 			"axon_msi: msi-translator doesn't point to a node\n");
@@ -154,7 +155,6 @@ static struct axon_msic *find_msi_translator(struct pci_dev *dev)
 
 out_error:
 	of_node_put(dn);
-	of_node_put(tmp);
 
 	return msic;
 }