net/mlx5: Fix possible deadlock on rule deletion

Add missing call to up_write_ref_node() which releases the semaphore
in case the FTE doesn't have destinations, such in drop rule case.

Fixes: 465e7baa ("net/mlx5: Fix deletion of duplicate rules")
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/fs_core.c

@@ -2074,6 +2074,8 @@ void mlx5_del_flow_rules(struct mlx5_flow_handle *handle)
 		fte->node.del_hw_func = NULL;
 		up_write_ref_node(&fte->node, false);
 		tree_put_node(&fte->node, false);
+	} else {
+		up_write_ref_node(&fte->node, false);
 	}
 	kfree(handle);
 }