slim: msm: Support deferred response during system suspend

If runtime-pm does not get a chance to enter low-power mode before
system suspend is called, system suspend may need 2 passes since
power-off request needs to be sent to audio-DSP using QMI, and QMI
acquires wakelock if response is expected right-away.

Use Deferred-response during suspend to avoid 2 passes, and inquire
the power-off status when system resumes in that case.

CRs-Fixed: 2030850
Change-Id: I74fbb566186ed693f1d244e101f9205af48c3652
Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>