net/mlx4_core: Fix wrong calculation of free counters

The field res_free indicates the total number of counters which are
available for allocation (reserved and unreserved). Fixed a bug where
the reserved counters were subtracted from res_free before any
allocation was performed.

Before this fix, free counters which were not reserved could not be
allocated.

Fixes: 9de92c60 ("net/mlx4_core: Adjust counter grant policy in the resource tracker")
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Reviewed-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/resource_tracker.c

@@ -611,7 +611,6 @@ int mlx4_init_resource_tracker(struct mlx4_dev *dev)
 						MLX4_MAX_PORTS;
 				else
 					res_alloc->guaranteed[t] = 0;
-				res_alloc->res_free -= res_alloc->guaranteed[t];
 				break;
 			default:
 				break;