software node: Allow node creation without properties

Software nodes are not forced to have device properties.
Adding check to property_entries_dup() to make it possible
to create software nodes that don't have any properties.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/swnode.c

@@ -383,6 +383,9 @@ property_entries_dup(const struct property_entry *properties)
 	int i, n = 0;
 	int ret;
 
+	if (!properties)
+		return NULL;
+
 	while (properties[n].name)
 		n++;