clk: qcom: clk-rpmh: add clk-rpmh driver

Add the clock RPMh driver to support voting for ARC and VRM
managed clock resources on some Qualcomm Technologies, Inc.
SoCs.

Change-Id: If8cd5e10400a2071c6492f45ff30ad4665a84084
Signed-off-by: David Collins <collinsd@codeaurora.org>