net/mlx5e: Err if asked to mirror a goto chain tc eswitch rule

Currently we are not supporting this and not err-ing on that either.

For now, just err if asked to do that.

Fixes: bf07aa73 ('net/mlx5e: Support offloading tc priorities and chains for eswitch flows')
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reported-by: Eli Britstein <elibr@mellanox.com>
Reviewed-by: Eli Britstein <elibr@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>