net/mlx5e: Create IPsec table with tunnel support only when encap is disabled

Current hardware doesn't support double encapsulation which is
happening when IPsec packet offload tunnel mode is configured
together with eswitch encap option.

Any user attempt to add new SA/policy after he/she sets encap mode, will
generate the following FW syndrome:

 mlx5_core 0000:08:00.0: mlx5_cmd_out_err:803:(pid 1904): CREATE_FLOW_TABLE(0x930) op_mod(0x0) failed,
 status bad parameter(0x3), syndrome (0xa43321), err(-22)

Make sure that we block encap changes before creating flow steering tables.
This is applicable only for packet offload in tunnel mode, while packet
offload in transport mode and crypto offload, don't have such limitation
as they don't perform encapsulation.

Reviewed-by: Raed Salem <raeds@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>