src/mb: Add SPDX identifiers to files missing them

This adds SPDX identifiers to the remaining source files in the
mainboard directory that don't already have them.

Change-Id: I1adc204624f3ab6fcafd8fbb239e6d69e057973a
Signed-off-by: Martin Roth <martin.roth@amd.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/66498
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@amd.corp-partner.google.com>

src/mainboard/asus/p8x7x-series/acpi/superio.asl

@@ -1 +1,3 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
 #include <drivers/pc80/pc/ps2_controller.asl>

src/mainboard/emulation/qemu-i440fx/acpi.h

@@ -1,2 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
 unsigned long northbridge_write_acpi_tables(struct device *device,
 					    unsigned long start);

src/mainboard/google/kahlee/variants/grunt/include/variant/ec.h

@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
 #include <baseboard/ec.h>
 
 /* Enable EC backed Keyboard Backlight in ACPI */

src/mainboard/lenovo/t400/acpi/ec.asl

@@ -1,2 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
 #include <ec/lenovo/h8/acpi/ec.asl>
 #include <ec/lenovo/h8/acpi/thinkpad_bat_thresholds_24.asl>

src/mainboard/lenovo/x200/acpi/ec.asl

@@ -1,2 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
 #include <ec/lenovo/h8/acpi/ec.asl>
 #include <ec/lenovo/h8/acpi/thinkpad_bat_thresholds_24.asl>

src/mainboard/msi/h81m-p33/acpi/superio.asl

@@ -1 +1,3 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
 #include <drivers/pc80/pc/ps2_controller.asl>

src/mainboard/packardbell/ms2290/acpi/superio.asl

@@ -1 +1,3 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
 #include <drivers/pc80/pc/ps2_controller.asl>

src/soc/example/min86/chip.c

@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
 #include <device/device.h>
 
 struct chip_operations soc_example_min86_ops = { NULL };