Pull ntb updates from Jon Mason:
 "Support for the switchtec ntb and related changes. Also, a couple of
  bug fixes"

[ The timing isn't great. I had asked people to send me pull requests
  before my family vacation, and this code has not even been in
  linux-next as far as I can tell. But Logan Gunthorpe pleaded for its
  inclusion because the Switchtec driver has apparently been around for
  a while, just never in linux-next - Linus ]

* tag 'ntb-4.15' of git://github.com/jonmason/ntb:
  ntb: intel: remove b2b memory window workaround for Skylake NTB
  NTB: make idt_89hpes_cfg const
  NTB: switchtec_ntb: Update switchtec documentation with notes for NTB
  NTB: switchtec_ntb: Add memory window support
  NTB: switchtec_ntb: Implement scratchpad registers
  NTB: switchtec_ntb: Implement doorbell registers
  NTB: switchtec_ntb: Add link management
  NTB: switchtec_ntb: Add skeleton NTB driver
  NTB: switchtec_ntb: Initialize hardware for doorbells and messages
  NTB: switchtec_ntb: Initialize hardware for memory windows
  NTB: switchtec_ntb: Introduce initial NTB driver
  NTB: Add check and comment for link up to mw_count() and mw_get_align()
  NTB: Ensure ntb_mw_get_align() is only called when the link is up
  NTB: switchtec: Add link event notifier callback
  NTB: switchtec: Add NTB hardware register definitions
  NTB: switchtec: Export class symbol for use in upper layer driver
  NTB: switchtec: Move structure definitions into a common header
  ntb: update maintainer list for Intel NTB driver