Revert "soc:qcom: Synchronize service notifier task's"

This reverts 'commit 79618505 ("soc:qcom: Synchronize
service notifier task's")'

This commit was made for synchronizing two notifier tasks that
were in race in back to back ADSP SSR testing. The change was to
synchronize two threads by queuing both threads in dedicated work
queue. However this caused certain corner case timing issues
in notification to clients of ADSP PD. So, revert it.

Change-Id: I69b27e2e4529b5f45ce0cc1f4a036412cbf5fab1
Signed-off-by: Avaneesh Kumar Dwivedi <akdwived@codeaurora.org>