msm: npu: Adjust timing to send notification to DSP

Notification to dsp that NPU powers off needs to be done when NPU
is alive no matter npu is in ssr state or not. And all dsp
notifications need to be protected to avoid to be sent after NPU
powers off.

Change-Id: I7cd22fa947f2a5c4798f8c31a6961273f00132ec
Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>