soc/intel: Include gfx.asl from northbridge

The iGPU is on the northbridge or system agent, not the southbridge.

Change-Id: Ic63a7ad532fd1faa8e90d44bf7269040fa901757
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49123
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

src/soc/intel/skylake/acpi/pch.asl

@@ -66,8 +66,5 @@ Method (_OSC, 4)
 #include <soc/intel/common/acpi/sgx.asl>
 #endif
 
-/* Integrated graphics 0:2.0 */
-#include <drivers/intel/gma/acpi/gfx.asl>
-
 /* Intel Power Engine Plug-in */
 #include <soc/intel/common/block/acpi/acpi/pep.asl>

src/soc/intel/skylake/acpi/systemagent.asl

@@ -322,3 +322,6 @@ Device (PDRC)
 		Return (BUF0)
 	}
 }
+
+/* Integrated graphics 0:2.0 */
+#include <drivers/intel/gma/acpi/gfx.asl>