net/mlx5e: Fix port tunnel GRE entropy control

GRE entropy calculation is a single bit per card, and not per port.
Force disable GRE entropy calculation upon the first GRE encap rule,
and release the force at the last GRE encap rule removal. This is done
per port.

Fixes: 97417f61 ("net/mlx5e: Fix GRE key by controlling port tunnel entropy calculation")
Signed-off-by: Eli Britstein <elibr@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>