net/mlx5: Remove ipsec vs. ipsec offload file separation

The IPsec won't be initialized at all if device doesn't support IPsec
offload. It means that we can combine the ipsec.c and ipsec_offload.c
files to one file. Such change will allow us to remove ipsec_ops
indirection.

Link: https://lore.kernel.org/r/d0ac1fb7b14c10ae20a21ae17a393ee860c72ac3.1649232994.git.leonro@nvidia.com


Reviewed-by: Raed Salem <raeds@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>