ARM: dts: qcom-msm8660: align RPM regulators node name with bindings

Node names should be generic and new DT schema expects RPM regulators
node to be just "regulators".

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221005-mdm9615-pinctrl-yaml-v3-5-e5e045644971@linaro.org