net/mlx5e: Drop XFRM state lock when modifying flow steering

XFRM state which is changed to be XFRM_STATE_EXPIRED doesn't really
need to hold lock while modifying flow steering rules to drop traffic.

That state can be deleted only and as such mlx5e_ipsec_handle_tx_limit()
work will be canceled anyway and won't run in parallel.

Fixes: b2f7b01d

 ("net/mlx5e: Simulate missing IPsec TX limits hardware functionality")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>