dt-bindings: arm: mediatek: Add MT8186 Steelix Chromebook

Add an entry for the MT8186 based Steelix Chromebook, also known as the
Lenovo 300e Yoga Chromebook Gen 4.
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240126083802.2728610-4-wenst@chromium.orgSigned-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Documentation/devicetree/bindings/arm/mediatek.yaml

@@ -235,6 +235,13 @@ properties:
           - enum:
               - mediatek,mt8183-pumpkin
           - const: mediatek,mt8183
+      - description: Google Steelix (Lenovo 300e Yoga Chromebook Gen 4)
+        items:
+          - enum:
+              - google,steelix-sku131072
+              - google,steelix-sku131073
+          - const: google,steelix
+          - const: mediatek,mt8186
       - description: Google Tentacruel (ASUS Chromebook CM14 Flip CM1402F)
         items:
           - const: google,tentacruel-sku262147