net: Fix ndo_setup_tc comment

Commit 16e5cc64

 ("net: rework setup_tc ndo op to consume
general tc operand") changed the ndo_setup_tc() signature, but did not
update the comments in netdevice.h, so do that now.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>