dt-bindings: phy: qcom,sc8280xp-qmp-ufs-phy: fix msm899[68] power-domains

The Qualcomm MSM8996 and MSM8998 platforms don't have separate power
domain for the UFS PHY. Replace required:power-domains with the
conditional schema.

Fixes: dc5cb635 ("dt-bindings: phy: migrate QMP UFS PHY bindings to qcom,sc8280xp-qmp-ufs-phy.yaml")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240501-qcom-phy-fixes-v1-2-f1fd15c33fb3@linaro.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>