dt-bindings: memory: mtk-smi: Correct minItems to 2 for the gals clocks

Mute the warning from "make dtbs_check":

larb@14017000: clock-names: ['apb', 'smi'] is too short
arch/arm64/boot/dts/mediatek/mt8183-evb.dt.yaml
arch/arm64/boot/dts/mediatek/mt8183-kukui-jacuzzi-burnet.dt.yaml
...

larb@16010000: clock-names: ['apb', 'smi'] is too short
arch/arm64/boot/dts/mediatek/mt8183-evb.dt.yaml
arch/arm64/boot/dts/mediatek/mt8183-kukui-jacuzzi-burnet.dt.yaml

larb@17010000: clock-names: ['apb', 'smi'] is too short
arch/arm64/boot/dts/mediatek/mt8183-evb.dt.yaml
arch/arm64/boot/dts/mediatek/mt8183-kukui-jacuzzi-burnet.dt.yaml

If a platform's larb supports gals, there will be some larbs have one
more "gals" clock while the others still only need "apb"/"smi" clocks,
then the minItems for clocks and clock-names are 2.

Fixes: 27bb0e42855a ("dt-bindings: memory: mediatek: Convert SMI to DT schema")
Signed-off-by: Yong Wu <[e-mail]>
Reviewed-by: AngeloGioacchino Del Regno <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

Documentation/devicetree/bindings/memory-controllers/mediatek,smi-larb.yaml

···
     then:
       properties:
         clocks:
-          minItems: 3
+          minItems: 2
           maxItems: 3
         clock-names:
+          minItems: 2
           items:
             - const: apb
             - const: smi