Add support for booting the Audio and Compute DSPs found in Qualcomm's
SDM845 platform.

As with the previous platforms the power rail handling needs to be
updated once the appropriate support lands upstream.
Acked-by: Rob Herring <robh@kernel.org>
Tested-by: Sibi Sankar <sibis@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>