Setting '/proc/sys/net/ipv4/igmp_max_memberships' is not enough.
We must pass the max_groups parameter to the mcproxy to prevent MFC
entries from being added to mr_table and packet forwarding for extra
groups.
We also need to increase max_groups, since mcproxy always subscribe
two service groups - ALL-ROUTERS (224.0.0.2) and
ALL-IGMPv3-MC-ROUTERS (224.0.0.22).
Script for generating mcast stats is moved from common to platform
specific files. The logic for generating mcast stats on non broadcom
platforms is different and the stats format is also different.
For generating stats we are are sending SIGUSR1 signal to mcproxy
process which then writes multicast stats to /tmp/igmp_snooping_stats.
