igmp: Namespaceify igmp_llm_reports sysctl knob

This was initially introduced in df2cf4a78e ("IGMP: Inhibit
reports for local multicast groups") by defining the sysctl in the
ipv4_net_table array, however it was never implemented to be
namespace aware. Fix this by changing the code accordingly.

Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netns/ipv4.h

@@ -110,6 +110,7 @@ struct netns_ipv4 {
 
 	int sysctl_igmp_max_memberships;
 	int sysctl_igmp_max_msf;
+	int sysctl_igmp_llm_reports;
 
 	struct ping_group_range ping_group_range;