net/mlx5e: Remove redundant hashtable lookup in configure flower

We will never find a flow with the same cookie as cls_flower always
allocates a new flow and the cookie is the allocated memory address.

Fixes: e3a2b7ed

 ("net/mlx5e: Support offload cls_flower with drop action")
Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Hadar Hen Zion <hadarh@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>