arm64: dts: mediatek: cherry: Add keyboard mapping for the top row

Chromebooks' embedded keyboards differ from standard layouts for the
top row, as this one doesn't have the standard function keys but
shortcuts instead: map these keys to achieve the functionality that
is pictured on the printouts.
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20220902081156.38526-5-angelogioacchino.delregno@collabora.comSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>

arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi

@@ -821,3 +821,33 @@ &xhci3 {
 
 #include <arm/cros-ec-keyboard.dtsi>
 #include <arm/cros-ec-sbs.dtsi>
+
+&keyboard_controller {
+	function-row-physmap = <
+		MATRIX_KEY(0x00, 0x02, 0)	/* T1 */
+		MATRIX_KEY(0x03, 0x02, 0)	/* T2 */
+		MATRIX_KEY(0x02, 0x02, 0)	/* T3 */
+		MATRIX_KEY(0x01, 0x02, 0)	/* T4 */
+		MATRIX_KEY(0x03, 0x04, 0)	/* T5 */
+		MATRIX_KEY(0x02, 0x04, 0)	/* T6 */
+		MATRIX_KEY(0x01, 0x04, 0)	/* T7 */
+		MATRIX_KEY(0x02, 0x09, 0)	/* T8 */
+		MATRIX_KEY(0x01, 0x09, 0)	/* T9 */
+		MATRIX_KEY(0x00, 0x04, 0)	/* T10 */
+	>;
+
+	linux,keymap = <
+		MATRIX_KEY(0x00, 0x02, KEY_BACK)
+		MATRIX_KEY(0x03, 0x02, KEY_REFRESH)
+		MATRIX_KEY(0x02, 0x02, KEY_ZOOM)
+		MATRIX_KEY(0x01, 0x02, KEY_SCALE)
+		MATRIX_KEY(0x03, 0x04, KEY_SYSRQ)
+		MATRIX_KEY(0x02, 0x04, KEY_BRIGHTNESSDOWN)
+		MATRIX_KEY(0x01, 0x04, KEY_BRIGHTNESSUP)
+		MATRIX_KEY(0x02, 0x09, KEY_MUTE)
+		MATRIX_KEY(0x01, 0x09, KEY_VOLUMEDOWN)
+		MATRIX_KEY(0x00, 0x04, KEY_VOLUMEUP)
+
+		CROS_STD_MAIN_KEYMAP
+	>;
+};