arm64: dts: qcom: msm8998-fxtec: Add QUSB2PHY VDD supply

arm64: dts: qcom: msm8998-fxtec: Add QUSB2PHY VDD supply

Set the supply as required by bindings, to silence the warning:

'vdd-supply' is a required property

The value is inferred from MTP schematics, but it shouldn't change
between boards due to specific electrical characteristics.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250327-topic-more_dt_bindings_fixes-v2-6-b763d958545f@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>