soc: qcom: service-notifier: use worker thread to send SSR notification

In some rare scenarios, observed dead lock due to clients blocked on
SSR notification. To avoid dead lock, use worker thread to send SSR
notification in case of SSR event.

Change-Id: I832fabce7569b1b8b966b7c49cda1b00cff2c472
Signed-off-by: Avaneesh Kumar Dwivedi <akdwived@codeaurora.org>