net: sched: change return value of ndo_setup_tc for driver supporting mqprio only

Change the return value from -EINVAL to -EOPNOTSUPP. The rest of the
drivers have it like that, so be aligned.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>