v2:
a) Also send ipv4 igmp messages with TC_PRIO_CONTROL

Cc: William Manley <william.manley@youview.com>
Cc: Lukas Tribus <luky-37@hotmail.com>
Acked-by: NBenjamin LaHaise <bcrl@kvack.org>
Signed-off-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>