clk: qcom: clk-rpmh: Add QCOM RPMh clock driver

Add the RPMh clock driver to control the RPMh managed clock resources on
some of the Qualcomm Technologies, Inc. SoCs.

Signed-off-by: Taniya Das <tdas@codeaurora.org>
[sboyd@kernel.org: Clean up whitespace, indentation, remove
cmd_db_ready check]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>