fix erb local variable warning

    Warning: Variable access via 'udev_log' is deprecated. Use '@udev_log' instead. template[/etc/puppet/modules/udev/templates/udev.conf.erb]:4

templates/udev.conf.erb

@@ -1,4 +1,4 @@
 # The initial syslog(3) priority: "err", "info", "debug" or its
 # numerical equivalent. For runtime debugging, the daemons internal
 # state can be changed with: "udevadm control --log-priority=<value>".
-udev_log="<%= udev_log %>"
+udev_log="<%= @udev_log %>"