dt-bindings: power: Add rpm power domain bindings for sdx55

Add RPM power domain bindings for the SDX55 SoC

Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20201126092711.1084518-1-vkoul@kernel.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>