net/mlx5e: Fix wrong tc flag used when set hw-tc-offload off

The cited commit reintroduced the ability to set hw-tc-offload
in switchdev mode by reusing NIC mode calls without modifying it
to support both modes, this can cause an illegal memory access
when trying to turn hw-tc-offload off.

Fix this by using the right TC_FLAG when checking if tc rules
are installed while disabling hw-tc-offload.

Fixes: d3cbd425

 ("net/mlx5e: Add ndo_set_feature for uplink representor")
Signed-off-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>