ARM: dts: qcom: msm8974-sony: Enable LPG

Both Castor and Honami has RGB LEDs driven by the PM8941 LPG, define
these.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Link: https://lore.kernel.org/r/20220713212309.130230-3-bjorn.andersson@linaro.org