[POWERPC] Make partitions optional in physmap_of

The latest physmap_of driver has a small error where it will fail the probe
with:

physmap-flash: probe of fff00000.small-flas failed with error -2

if there are no partition subnodes in the device tree and the old style binding
is not used.  Since partition definitions are optional, the probe should still
succeed.
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>

drivers/mtd/maps/physmap_of.c

@@ -142,6 +142,8 @@ static int __devinit process_partitions(struct physmap_flash_info *info,
 		}
 	} else {
 		nr_parts = parse_obsolete_partitions(dev, info, dp);
+		if (nr_parts == -ENOENT)
+			nr_parts = 0;
 	}
 
 	if (nr_parts < 0)