net: prestera: flower: fix destroy tmpl in chain

Fix flower destroy template callback to release template
only for specific tc chain instead of all chain tempaltes.

The issue was intruduced by previous commit that introduced
multi-chain support.

Fixes: fa5d824c ("net: prestera: acl: add multi-chain support offload")
Signed-off-by: Volodymyr Mytnyk <vmytnyk@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>