Bluetooth: Fix checking for HCI_SETUP flag when receiving mgmt commands

When the HCI_SETUP flag is set the controller has not yet been announced
over mgmt and therefore doesn't exist from that perspective. If we
nevertheless get a mgmt command for it we should respond with the
appropriate INVALID_INDEX error.

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