fill prio and protocol attr bits when parsing cls message

Otherwise, the filter we get from a cls cache can't be used
for removal.

Cc: Thomas Haller <thaller@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Thomas Haller <thaller@redhat.com>