catas_reset() uses a pointer to mthca_dev, but mthca_dev is not valid
after the call to __mthca_restart_one().

Based on a similar patch for mlx4 (634354d7, "mlx4: Fix access to
freed memory") by Vitaliy Gusev <vgusev@openvz.org>
Signed-off-by: NJack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>