[Skiboot] skiboot 5.9.4

[Stewart Smith]

skiboot-5.9.4
*************

skiboot 5.9.4 was released on Wednesday November 29th, 2017. It
replaces skiboot-5.9.3 as the current stable release in the 5.9.x
series.

Over skiboot-5.9.3, we have one NPU2/NVLink2 fix that works around a
potential glitch (the one skiboot-5.9.3 would hard crash on rather
than let a system continue to run until it mysteriously crashed later
on).

That fix is in two parts:

* npu2: hw-procedures: Change phy_rx_clock_sel values to recover
  from a potential glitch.

* npu2: hw-procedures: Manipulate IOVALID during training

  Ensure that the IOVALID bit for this brick is raised at the start of
  link training, in the reset_ntl procedure.

  Then, to protect us from a glitch when the PHY clock turns off or
  gets chopped, lower IOVALID for the duration of the phy_reset and
  phy_rx_dccal procedures.

-- 
Stewart Smith
OPAL Architect, IBM.