net: sched: choke: Remove unused inline function choke_set_classid

There's no callers in-tree anymore since commit 5952fde1 ("net:
sched: choke: remove dead filter classify code")

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>