Some old peer central controllers respond with Unknown
Response PDU to our local Slave Initiated Feature Request
after the peer initiated the Encryption Setup Procedure.
The peer has voilated the Bluetooth Specification by sending
the Unknown Response during the Encryption Setup Procedure,
but as a workaround to IOP with such controller our local
implementation is updated to not disconnect the connection
but accept the voilating Unknown Response PDU.
Relates to #12362.
Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>
5f2099fb63