remoteproc: sysmon: Ensure remote notification ordering

The reliance on the remoteproc's state for determining when to send
sysmon notifications to a remote processor is racy with regard to
concurrent remoteproc operations.

Further more the advertisement of the state of other remote processor to
a newly started remote processor might not only send the wrong state,
but might result in a stream of state changes that are out of order.

Address this by introducing state tracking within the sysmon instances
themselves and extend the locking to ensure that the notifications are
consistent with this state.

Fixes: 1f36ab3f ("remoteproc: sysmon: Inform current rproc about all active rprocs")
Fixes: 1877f54f ("remoteproc: sysmon: Add notifications for events")
Fixes: 1fb82ee8 ("remoteproc: qcom: Introduce sysmon")
Cc: stable@vger.kernel.org
Reviewed-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
Link: https://lore.kernel.org/r/20201122054135.802935-2-bjorn.andersson@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>