soc: qcom: apr: Add GPR support

Qualcomm Generic Packet router aka GPR is the IPC mechanism found
in AudioReach next generation signal processing framework to perform
command and response messages between various processors.

GPR has concepts of static and dynamic port, all static services like
APM (Audio Processing Manager), PRM (Proxy resource manager) have
fixed port numbers where as dynamic services like graphs have dynamic
port numbers which are allocated at runtime. All GPR packet messages
will have source and destination domain and port along with opcode
and payload.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210927135559.738-6-srinivas.kandagatla@linaro.org