radio-iris: Serialize the call to fm_ops_release function

fm_ops_release function can be called twice in parallel and can free
resources before second call complete execution.
This will lead to crashes.

Change-Id: Ie19035c10931d9336599e0e3872ef46ab77e1527
Signed-off-by: Kamal Negi <kamaln@codeaurora.org>