Be symmetric to hashtable insert and remove filter from hashtable only
in case skip sw flag is not set.

Fixes: e69985c6 ("net/sched: cls_flower: Introduce support in SKIP SW flag")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Amir Vadai <amir@vadai.me>
Signed-off-by: David S. Miller <davem@davemloft.net>