baytrail: Add XHCI initialization

This adds required steps to initialize the XHCI controller
on the baytrail platform.

Actually using XHCI is causing lots of bad behavior including
apparent memory corruption.

BUG=chrome-os-partner:23635
BRANCH=rambi
TEST=build and boot on rambi

Change-Id: Ic43e04f4b47e107ec3bb0c387a9fc72c3cae0271
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/175511
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/4929
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/soc/intel/baytrail/Makefile.inc

@@ -31,6 +31,7 @@ ramstage-y += pmutil.c
 smm-y += pmutil.c
 smm-y += smihandler.c
 ramstage-y += smm.c
+ramstage-y += xhci.c
 ramstage-y += southcluster.c
 ramstage-$(CONFIG_HAVE_REFCODE_BLOB) += refcode.c
 ramstage-y += sata.c