dt-bindings: phy: mediatek,hdmi-phy: Fix clock output names for MT8195

For all of the HDMI PHYs compatible with the one found on MT8195
the output clock has a different datasheet name and specifically
it is called "hdmi_txpll", differently from the older HDMI PHYs
which output block is called "hdmitx_dig_cts".

Replace clock output name string check by max item number one to allow
the new name on all of the HDMI PHY IPs that are perfectly compatible
with MT8195.

[Louis-Alexis Eyraud: split patch, addressed previous feedback from
mailing list, and reworded description]

Fixes: c78fe54 ("dt-bindings: phy: mediatek: hdmi-phy: Add mt8195 compatible")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20251217-mtk-genio-evk-hdmi-support-v2-1-a994976bb39a@collabora.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

Author: AngeloGioacchino Del Regno

Documentation/devicetree/bindings/phy/mediatek,hdmi-phy.yaml

@@ -42,8 +42,7 @@ properties:
       - const: pll_ref
 
   clock-output-names:
-    items:
-      - const: hdmitx_dig_cts
+    maxItems: 1
 
   "#phy-cells":
     const: 0