net/mlx5: allow pattern start from IP
net/mlx5: allow pattern start from IP

Some applications, i.e. OVS, have rule like:

[1] pattern ipv4 / end actions ...

which intends to match ipv4 only on non-vlan ethernet and MLX5 NIC
supports this.

So PMD should accept this.

Fixes: 906a2efae8da ("net/mlx5: validate flow rule item order")
Cc: stable@dpdk.org

Signed-off-by: Xiaoyu Min <03352a7947822e04037757091119acfbe3910106@mellanox.com>
Acked-by: Ori Kam <dd654df5de18ba542acfaea52fe1a0799392087d@mellanox.com>
Acked-by: Viacheslav Ovsiienko <5b8db9bb93a9a9aefc8828f79604d1fe963a53dd@mellanox.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk