of: address: Don't fail a lookup just because a node has no reg property

Sometimes it doesn't make any sense for a node to have an address.
In this case device lookup will always be unsuccessful because we
currently assume every node will have a reg property. This patch
changes the semantics so that the resource address and the lookup
address will only be compared if one exists.

Things like AUXDATA() rely on of_dev_lookup to return the lookup
entry of a particular device in order to do things like apply
platform_data to a device. However, this is currently broken for
nodes which do not have a reg property, meaning that platform_data
can not be passed in those cases.
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/of/platform.c

@@ -317,10 +317,9 @@ static const struct of_dev_auxdata *of_dev_lookup(const struct of_dev_auxdata *l
 	for(; lookup->compatible != NULL; lookup++) {
 		if (!of_device_is_compatible(np, lookup->compatible))
 			continue;
-		if (of_address_to_resource(np, 0, &res))
-			continue;
-		if (res.start != lookup->phys_addr)
-			continue;
+		if (!of_address_to_resource(np, 0, &res))
+			if (res.start != lookup->phys_addr)
+				continue;
 		pr_debug("%s: devname=%s\n", np->full_name, lookup->name);
 		return lookup;
 	}