powerpc: Guard print_device_node_tree() with #if 0

Currently print_device_node_tree() isn't called but it can be useful for
debugging.  Leave the function there but hide it behind '#if 0' to save
it being rewritten.  If you want to call it you're already editing this
file anyway. ;P
Signed-off-by: NTony Breeds <tony@bakeyournoodle.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

arch/powerpc/platforms/pseries/eeh_driver.c

@@ -41,7 +41,7 @@ static inline const char * pcid_name (struct pci_dev *pdev)
 	return "";
 }
 
-#ifdef DEBUG
+#if 0
 static void print_device_node_tree(struct pci_dn *pdn, int dent)
 {
 	int i;