net: replace continue with break to reduce unnecessary loop in xxx_xmarksources

The conditional which decides to skip inactive filters does not
change with the change of loop index, so it is unnecessary to
check them many times.

Signed-off-by: RongQing.Li <roy.qing.li@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc net/ipv4/igmp.c
Simple merge

diff --cc net/ipv6/mcast.c
Simple merge