q->link.block is not initialized, that leads to EINVAL when one tries to
add filter there. So initialize it properly.

This can be reproduced by:
$ tc qdisc add dev eth0 root handle 1: cbq avpkt 1000 rate 1000Mbit bandwidth 1000Mbit
$ tc filter add dev eth0 parent 1: protocol ip prio 100 u32 match ip protocol 0 0x00 flowid 1:1
Reported-by: NJaroslav Aster <jaster@redhat.com>
Reported-by: NIvan Vecera <ivecera@redhat.com>
Fixes: 6529eaba ("net: sched: introduce tcf block infractructure")
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Acked-by: NEelco Chaudron <echaudro@redhat.com>
Reviewed-by: NIvan Vecera <ivecera@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>