The work item will attempt to dereference pointers that have been nulled
by the backend.
To avoid that, wait until all items currently on the queue have been
processed.
The symptom is a busfault on ARM, and is "fixed" by adding a
`k_msleep(1)` right before `ipc_service_deregister_endpoint()`. This
will in effect do the same thing as this patch, and allow the scheduler
to run the work item on the ipc workqueue.
Signed-off-by: Jonathan Rico <jonathan.rico@nordicsemi.no>
f24a01e6d1