Bluetooth: controller: Fix channel map check in CONNECT_IND PDU

Fix the leak of node rx buffer used to generate the
connection complete and CSA#2 event introduced in the
commit 4a5f263e ("Bluetooth: controller: split: Validate
chan map and hop value") and the
commit 94d5f085 ("Bluetooth: controller: fixing error
re. all zero chmap in conn-ind").

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