soc: qcom: wda: Safe traversal of PS list

Previously delete/callback logic of ps list was not
protected from a race condition.

This changes qcom list traversal to use safe traversal to prevent
delete from causing an exception in callback notification.

Change-Id: I5259308947d895835c18e582037bd3de274dd50a
Acked-by: Raul Martinez <mraul@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>