[Skiboot] skiboot 5.9.1

[Stewart Smith]

skiboot-5.9.1
*************

skiboot 5.9.1 was released on Tuesday November 14th, 2017. It replaces
skiboot-5.9 as the current stable release in the 5.9.x series.

Over skiboot-5.9, we have two NPU2 (NVLink2) fixes and two XIVE bug
fixes:

* npu2: hw-procedures: Refactor reset_ntl procedure

  Change the implementation of reset_ntl to match the latest
  programming guide documentation.

* npu2: hw-procedures: Add phy_rx_clock_sel()

  Change the RX clk mux control to be done by software instead of HW.
  This avoids glitches caused by changing the mux setting.

* xive: Fix ability to clear some EQ flags

  We could never clear "unconditional notify" and "escalate"

* xive: Update inits for DD2.0

  This updates some inits based on information from the HW designers.
  This includes enabling some new DD2.0 features that we don't yet
  exploit.

-- 
Stewart Smith
OPAL Architect, IBM.