dt-bindings: power: rpmpd: Add SM6375 power domains

Add the bindings for SM6375 RPMPDs.

Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220716193201.455728-1-konrad.dybcio@somainline.org