net/mlx5: fix error return code in mlx5e_tc_nic_init()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: aedd133d ("net/mlx5e: Support CT offload for tc nic flows")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>