Add fastrpc nodes for sDSP, cDSP, and aDSP.

Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210928140929.2549459-2-bhupesh.sharma@linaro.org