ARM: dts: qcom: msm8974: do not use underscore in node name (again)

Align RPM requests node with DT schema by using hyphen instead of
underscore.

Fixes: f300826d ("ARM: dts: qcom-msm8974: Sort and clean up nodes")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230410175232.22317-1-krzysztof.kozlowski@linaro.org