ASoC: wcd_cpe_core: Fix handling of deregister event

All clients to cpe service can deregister either in normal case when the
session is torn down or they can deregister during SSR scenarios. Fix
the handling of deregister event to mark the ready status of CPE in case
of both CPE SSR event and when the underlying bus is down. This fixes
the issue where CPE is not ready for online after the underlying bus
becomes ready.

CRs-fixed: 741604
Change-Id: I3331244dfba38386c8596d4a0ea6161f8637c175
Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>