lynxpoint: Route all USB ports to XHCI in finalize step

This commit adds a new Kconfig option for the LynxPoint
southbridge that will have coreboot route all of the USB
ports to the XHCI controller in the finalize step (i.e.
after the bootloader) and disable the EHCI controller(s).

Additionally when doing this the XHCI USB3 ports need
to be put into an expected state on resume in order to make
the kernel state machine happy.

Part of this could also be done in depthcharge but there
are also some resume-time steps required so it makes sense
to keep it all together in coreboot.

This can theoretically save ~100mW at runtime.

BUG=chrome-os-partner:21342
BRANCH=falco,peppy
CQ-DEPEND=CL:63800
TEST=emerge-falco chromeos-coreboot-falco

Verify that the EHCI controller is not found in Linux and
that booting from USB still works.

Change-Id: I3ddfecc0ab12a4302e6034ea8d13ccd8ea2a655d
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/63802
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/include/cpu/x86/smm.h

@@ -372,6 +372,7 @@ typedef struct {
 #define APM_CNT_ACPI_ENABLE	0xe1
 #define APM_CNT_MBI_UPDATE	0xeb
 #define APM_CNT_GNVS_UPDATE	0xea
+#define APM_CNT_FINALIZE	0xcb
 #define APM_STS		0xb3
 
 /* SMI handler function prototypes */