net/mlx5e: IPsec: Fix tunnel mode crypto offload for non TCP/UDP traffic

IPsec Tunnel mode crypto offload software parser (SWP) setting in data
path currently always set the inner L4 offset regardless of the
encapsulated L4 header type and whether it exists in the first place,
this breaks non TCP/UDP traffic as such.

Set the SWP inner L4 offset only when the IPsec tunnel encapsulated L4
header protocol is TCP/UDP.

While at it fix inner ip protocol read for setting MLX5_ETH_WQE_SWP_INNER_L4_UDP
flag to address the case where the ip header protocol is IPv6.

Fixes: f1267798

 ("net/mlx5: Fix checksum issue of VXLAN and IPsec crypto offload")
Signed-off-by: Raed Salem <raeds@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>