net/mlx4_core: Add bad-cable event support

If the firmware can detect a bad cable, allow it to generate an
event, and print the problem in the log.

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>