baytrail: Add default _OSC method

This is needed to let the kernel know it can control everything
and not to disable features.

BUG=chrome-os-partner:23505
BRANCH=rambi
TEST=build and boot on rambi

Change-Id: I40ff15bb931a9be7c31509ec84489083b5af0a82
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/175629
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/4939
Tested-by: build bot (Jenkins)

src/soc/intel/baytrail/acpi/southcluster.asl

@@ -193,3 +193,20 @@ Device (PDRC)
 		Return(PDRS)
 	}
 }
+
+Method (_OSC, 4)
+{
+	/* Check for proper GUID */
+	If (LEqual (Arg0, ToUUID("33DB4D5B-1FF7-401C-9657-7441C03DD766")))
+	{
+		/* Let OS control everything */
+		Return (Arg3)
+	}
+	Else
+	{
+		/* Unrecognized UUID */
+		CreateDWordField (Arg3, 0, CDW1)
+		Or (CDW1, 4, CDW1)
+		Return (Arg3)
+	}
+}