ipv6: Export nf_ct_frag6_consume_orig()

This is needed in openvswitch to fix an skb leak in the next patch.

Signed-off-by: Joe Stringer <joestringer@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>