xhci: Switch Intel Lynx Point LP ports to EHCI on shutdown.

xhci: Switch Intel Lynx Point LP ports to EHCI on shutdown.

commits c09ec25d3684cad74d851c0f028a495999591279 and
0a939993bff117d3657108ca13b011fc0378aedb upstream.

The same issue like with Panther Point chipsets. If the USB ports are
switched to xHCI on shutdown, the xHCI host will send a spurious interrupt,
which will wake the system. Some BIOS have work around for this, but not all.
One example is Compulab's mini-desktop, the Intense-PC2.

The bug can be avoided if the USB ports are switched back to EHCI on
shutdown.

This patch should be backported to stable kernels as old as 3.12,
that contain the commit 638298dc66ea36623dbc2757a24fc2c4ab41b016
"xhci: Fix spurious wakeups after S5 on Haswell"

Signed-off-by: Denis Turischev <denis@compulab.co.il>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Patch "xhci: Switch Intel Lynx Point ports to EHCI on shutdown."
commit c09ec25d3684cad74d851c0f028a495999591279 is not fully correct

It switches both Lynx Point and Lynx Point-LP ports to EHCI on shutdown.
On some Lynx Point machines it causes spurious interrupt,
which wake the system: bugzilla.kernel.org/show_bug.cgi?id=76291

On Lynx Point-LP on the contrary switching ports to EHCI seems to be
necessary to fix these spurious interrupts.

Signed-off-by: Denis Turischev <denis@compulab.co.il>
Reported-by: Wulf Richartz <wulf.richartz@gmail.com>
Cc: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Combined the above commits and backported to 3.2: adjust context to
 apply after "xhci: Limit the spurious wakeup fix only to HP machines" and
 "xhci: no switching back on non-ULT Haswell"]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>