ip6_output: do skb ufo init for peeked non ufo skb as well

ip6_output: do skb ufo init for peeked non ufo skb as well

Now, if user application does:
sendto len<mtu flag MSG_MORE
sendto len>mtu flag 0
The skb is not treated as fragmented one because it is not initialized
that way. So move the initialization to fix this.

introduced by:
commit e89e9cf539a28df7d0eb1d0a545368e9920b34ac "[IPv4/IPv6]: UFO Scatter-gather approach"

Signed-off-by: Jiri Pirko <[email protected]>
Acked-by: Hannes Frederic Sowa <[email protected]>
Signed-off-by: David S. Miller <[email protected]>