Bluetooth: controller: split: Fix Enc setup reset on rejection

Fix reset of Encryption Procedure state on reception of
REJECT_IND and REJECT_EXT_IND.

This is a regression in commit 79cb6157 ("Bluetooth:
controller: split: Port Enc setup to be queueable")

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