Bluetooth: Fix opcode access in hci_complete

opcode to be accessed is in le16 format so convert it
first to cpu byte order.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>