Bluetooth: Controller: Fix Extended connection initiation assertion

Fix assertion on aux context release during extended
connection initiation when supporting multiple simultaneous
interleaved Extended scanning support.

Relates to commit a8065926 ("Bluetooth: Controller: Fix
to release aux context stored in node rx").

Relates to commit 193ce731 ("Bluetooth: Controller: Fix
missing resume of primary channel scanning").

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