Bluetooth: Make hci_send_to_sock usable for management control sockets

In order to send data to management control sockets the function should:

  - skip checks intended for raw HCI data and stack internal events
  - make sure RAW HCI data or stack internal events don't go to
    management control sockets

In order to accomplish this the patch adds a new member to the bluetooth
skb private data to flag skb's that are destined for management control
sockets.

Signed-off-by: Johan Hedberg <johan.hedberg@nokia.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>