Bluetooth: Controller: Fix auxiliary scan stop assertion check

Use a local variable to assert check on auxiliary context's
release.
Add missing volatile qualifier to the parent field of the
auxiliary scan context.
Under race condition a released aux context can be allocated
for reception of chain PDU of a periodic sync role, hence
fix the assertion check to consider that the released
context can be allocated to other roles.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>
2 files changed