net/mlx5: IPsec: make spdxcheck.py happy

Commit 2d64663c

 ("net/mlx5: IPsec: Add HW crypto offload support")
provided a proper SPDX license expression, but slipped in a typo.

Fortunately, ./scripts/spdxcheck.py warns:

  drivers/net/ethernet/mellanox/mlx5/core/accel/ipsec_offload.c: 1:39 \
  Invalid License ID: Linux-OpenIBt

Remove the typo and make spdxcheck.py happy.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>