net/mlx4_en: Fix double-release-range in tx-rings

The QP range is reserved as a single block. However, when freeing the
en resources, the tx-ring QPs are released both in mlx4_en_destroy_tx_ring
(one at a time) and in mlx4_en_free_resources (as a block release).

Fix by eliminating the one-at-a-time release in mlx4_en_destroy_tx_ring.

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>