dt-bindings: phy: fix dt_binding_check warning in mediatek, ufs-phy.yaml

This commit fixes the warning messages of make dt_binding_check from
newly added mediatek,mt8195-ufsphy in mediatek,ufs-phy.yaml

Signed-off-by: Seiya Wang <seiya.wang@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210319023427.16711-9-seiya.wang@mediatek.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>