net/mlx5: IPsec, Fix coverity issue

The cited commit introduced the following coverity issue at functions
mlx5_fpga_is_ipsec_device() and mlx5_fpga_ipsec_release_sa_ctx():
- bit_and_with_zero:
  accel_xfrm->attrs.action & MLX5_ACCEL_ESP_ACTION_DECRYPT is always 0.

As MLX5_ACCEL_ESP_ACTION_DECRYPT is not a bitwise flag and was wrongly
used with bitwise operation, the above expression is always zero value
as MLX5_ACCEL_ESP_ACTION_DECRYPT is zero.

Fix by using "==" comparison operator instead.

Fixes: 7dfee4b1 ("net/mlx5: IPsec, Refactor SA handle creation and destruction")
Signed-off-by: Raed Salem <raeds@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>