asoc: codecs: wsa881x: turn off PA at ssr

Register for a callback for ssr notification
and turn off PA at pre-ssr to protect speaker
from any turning off damage during SSR.

Change-Id: I286d9bdcbcba9561424a8f0d4a1e99a8492caf08
Signed-off-by: Karthikeyan Mani <kmani@codeaurora.org>