clk: qcom: smd-rpm: Drop MFD qcom-rpm reference

The MFD qcom-rpm interface is not used by this driver.  Drop the 'struct
qcom_rpm' reference and include of <dt-bindings/mfd/qcom-rpm.h>.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211031020715.21636-2-shawn.guo@linaro.org