ipv6: remove ipv6_statistics

commit 9261e5370112 (ipv6: making ip and icmp statistics per/namespace)
forgot to remove ipv6_statistics variable.

commit bc417d99bf27 (ipv6: remove stale MIB definitions) took care of
icmpv6_statistics & icmpv6msg_statistics

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Denis V. Lunev <den@openvz.org>
CC: Alexey Dobriyan <adobriyan@gmail.com>
CC: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ipv6_sockglue.c

@@ -55,8 +55,6 @@
 
 #include <asm/uaccess.h>
 
-DEFINE_SNMP_STAT(struct ipstats_mib, ipv6_statistics) __read_mostly;
-
 struct ip6_ra_chain *ip6_ra_chain;
 DEFINE_RWLOCK(ip6_ra_lock);