net/mlx5: fix RSS expand for IP-in-IP

net/mlx5: fix RSS expand for IP-in-IP

The RSS expand function for IP-in-IP tunnel type is missed,
which leads to create following flow failed:

   flow create 0 ingress pattern eth / ipv4 proto is 4 /
        ipv4 / udp / end actions rss queues 0 1 end level 2
	types ip ipv4-other udp ipv4 ipv4-frag end /
	mark id 221 / count / end

In order to make RSS expand function working correctly,
now the way to check whether a IP tunnel existing is to
check whether there is the second IPv4/IPv6 item and whether the
first IPv4/IPv6 item's next protocl is IPPROTO_IPIP/IPPROTO_IPV6.
For example:
  ... pattern eth / ipv4 proto is 4 / ipv4 / ....

Fixes: 5e33bebdd8d3 ("net/mlx5: support IP-in-IP tunnel")

Signed-off-by: Xiaoyu Min <jackmin@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>