IB/qib: New SERDES init routine and improvements to SI quality

Implement new SERDES initialization routine and improvements to signal
integrity -- disable LE1 adaptation, disable LOS after link-up, set
better SERDES parameters.

Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>