mlx4_core: Add link type autosensing

When a port's link is down (except to driver restart) and the port is
configured for auto sensing, we try to sense port link type (Ethernet
or InfiniBand) in order to determine how to initialize the port.  If
the port type needs to be changed, all mlx4 for the device interfaces
are unregistered and then registered again with the new port
types.  Sensing is done with intervals of 3 seconds.

Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>