net/sched: act_sample: Fix error path in init

Fix error path of in sample init, by releasing the tc hash in case of
failure in psample_group creation.

Fixes: 5c5670fa

 ("net/sched: Introduce sample tc action")
Reported-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Yotam Gigi <yotamg@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>