soc: qcom: pil: Allow timeouts for graceful subsystem shutdown

Currently, if a subsystem does not send a response through QMI
confirming that it has properly gone through its shutdown
sequence within a certain time, it is assumed that something
went wrong, and the subsystem could not shutdown gracefully.
However, for some subsystems, part of their shutdown sequence
may involve disabling the QMI service prior to sending the
response, and continuing the rest of the shutdown sequence
without any problems. The real indicator of an issue is not
receiving either an SMP2P interrupt or an QMI indication that
the subsystem has shutdown. Allow for timeouts to be
an acceptable cause of a graceful shutdown sequence, and wait
for either an SMP2P interrupt or QMI indication that indicate
whether the device has shutdown or not.

Change-Id: Id870f948f5e99a999965cf83ca225788e01eaf2e
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>