dt-bindings: power: qcom,rpmpd: document the Eliza RPMh Power Domains

Document the RPMh Power Domains on the Eliza Platform. It is not
compatible with any of the previous platforms, so dedicated compatible
string is needed.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>