[ICMP]: Simplify ICMP control socket creation.

Replace sock_create_kern with inet_ctl_sock_create.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>