commit 2f75e12c upstream.

Research has shown that commit a77fcf89 ("IB/qib: Use a single
txselect module parameter for serdes tuning") missed a key serdes init
sequence.

This patch add that sequence.
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>