dt-bindings: clock: Introduce QCOM RPMh clock bindings

Add RPMh clock device bindings for Qualcomm Technology Inc's SoCs. These
devices would be used for communicating resource state requests to control
the clocks managed by RPMh.

Signed-off-by: Taniya Das <tdas@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>