soc: swr-mstr: Avoid handling redundant swr wakeup events

It is sometimes observed that afe could send multiple wakeup
events at a time. Avoid this by handling wakeup event only once
per swr suspend.

Change-Id: Ieb9ed1b18c8c93cb7db4b75e3411cc25838be492
Signed-off-by: Ramprasad Katkam <katkam@codeaurora.org>