soc: qcom: aoss: Add debugfs interface for sending messages

In addition to the normal runtime commands, the Always On Processor
(AOP) provides a number of debug commands which can be used during
system debugging for things such as preventing power collapse or placing
floor votes for certain resources. Some of these are documented in the
Robotics RB5 "Debug AOP ADB" linked below.

Provide a debugfs interface for the developer/tester to send some of
these commands to the AOP, which allow the user to override the DDR
frequency, preventing power collapse of cx and ddr, and prevent AOSS
from going to sleep.

Link: https://docs.qualcomm.com/bundle/publicresource/topics/80-88500-3/85_Debugging_AOP_ADB.html


Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Reviewed-by: Chris Lew <quic_clew@quicinc.com>
Link: https://lore.kernel.org/r/20240117-qcom-aoss-debugfs-v2-v3-1-1aa779124822@quicinc.com


[bjorn: Dropped S_IWGRP from the debugfs files]
Signed-off-by: Bjorn Andersson <andersson@kernel.org>