dt-binding: remoteproc: Add QTI ADSP PIL bindings

Add devicetree bindings documentation file for Qualcomm
Technolgies Inc ADSP Peripheral Image Loader.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rohit kumar <rohitkr@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>