Bluetooth: Fix hci_sock_recvmsg when MSG_TRUNC is not set

Similar to bt_sock_recvmsg MSG_TRUNC shall be checked using the original
flags not msg_flags.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>