Bluetooth: Set conn state to BT_DISCONN to avoid multiple responses
This patch fixes a minor issue that two connection responses will be sent
for one L2CAP connection request. If the L2CAP connection request is first
blocked due to security reason and responded with reason "security block",
the state of the connection remains BT_CONNECT2. If a pairing procedure
completes successfully before the ACL connection is down, local host will
send another connection complete response. See the following packets
captured by hcidump.