net/mlx5e: Fix a couple error codes

If kvzalloc() fails then return -ENOMEM.  Don't return success.

Fixes: 3b20949c ("net/mlx5e: Add MACsec RX steering rules")
Fixes: e467b283 ("net/mlx5e: Add MACsec TX steering rules")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>