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>

src/mainboard/google/reef/mainboard.c

@@ -20,6 +20,7 @@
 #include <nhlt.h>
 #include <soc/gpio.h>
 #include <soc/nhlt.h>
+#include <vendorcode/google/chromeos/chromeos.h>
 #include "ec.h"
 #include "gpio.h"
 
@@ -83,6 +84,7 @@ static unsigned long mainboard_write_acpi_tables(
 static void mainboard_enable(device_t dev)
 {
 	dev->ops->write_acpi_tables = mainboard_write_acpi_tables;
+	dev->ops->acpi_inject_dsdt_generator = chromeos_dsdt_generator;
 }
 
 struct chip_operations mainboard_ops = {