chromeos mainboards: remove chromeos.asl

Use the ACPI generator for creating the Chrome OS gpio
package. Each mainboard has its own list of Chrome OS
gpios that are fed into a helper to generate the ACPI
external OIPG package.  Additionally, the common
chromeos.asl is now conditionally included based on
CONFIG_CHROMEOS.

Change-Id: I1d3d951964374a9d43521879d4c265fa513920d2
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/15909
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
diff --git a/src/southbridge/intel/lynxpoint/pch.h b/src/southbridge/intel/lynxpoint/pch.h
index a3cd811..8cae50a 100644
--- a/src/southbridge/intel/lynxpoint/pch.h
+++ b/src/southbridge/intel/lynxpoint/pch.h
@@ -19,6 +19,8 @@
 
 #include <arch/acpi.h>
 
+#define CROS_GPIO_DEVICE_NAME	"LynxPoint"
+
 /*
  * Lynx Point PCH PCI Devices:
  *