arm64: dts: qcom: ipq9574: remove MP5496 regulator references from SoC dtsi

arm64: dts: qcom: ipq9574: remove MP5496 regulator references from SoC dtsi

The 'cpu-supply' properties in the IPQ9574 SoC dtsi are referencing to
a regulator provided by an MP5496 PMIC via the RPM firmware which's node
is defined  externally in the common RDP dtsi file.

Since the PMIC is not part of the SoC it should not be referenced from
the SoC specific dtsi, so remove the properties from there and define
those in the common RDP dtsi instead.

While at it, also change the prefix of the label from 'ipq9574' to
'mp5496' to keep it consistent with the labels of the l{2,5} regulators
provided by the same PMIC.

No functional changes. According to dtx_diff there are no differences
between the ipq9574*.dtb files built with and without the change.

Signed-off-by: Gabor Juhos <j4g8y7@gmail.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260123-ipq9574-mp5496-cleanup-v1-1-9fa86f72b873@gmail.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>