net: sched: move TC_H_MAJ macro call into tcf_auto_prio

Call the helper from the function rather than to always adjust the
return value of the function.

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>