Bluetooth: Add LE scan type macros

This patch adds macros for active and passive LE scan type values. It
also removes the LE_SCAN_TYPE macro since it is not used anymore.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: LE connection state machine

This patch implements a state machine for carrying out the general
connection establishment procedure.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Change LE connection routine

In order to better support LE connection requirements, such as
multiple connections and re-connections, we should support the
general connection establishment procedure described in Core
spec. Today, we support only the direct connection establishment
procedure which has some limitations and, therefore, requires
extra connection management at user-space in order to support
LE connection requirements.

According to the spec, the general procedure is described as
follows: The host starts scanning for LE devices, once the
device we want to connect to is in-range, the host stops scanning
and initiates a connection. The procedure is terminated when the
connection is established or when the host terminates the procedure.

This patch changes the LE connection routine so we carry out the
general procedure instead of the direct procedure.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Handle hci_conn timeout in BT_CONNECT

If occurs a hci_conn timeout in BT_CONNECT state we should stop the
ongoing LE scan.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Track the number of hci_conn in BT_SCAN

In order to avoid traversing the hci_conn list every time we get an
advertising report, we should keep a counter of connections in
BT_SCAN state. This way, we only traverse the list if the counter
is greater from zero.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Initialize some hci_conn fields earlier

This patch moves some hci_conn fields initialization to hci_connect_le.
There is no reason we initialize them later at hci_le_create_connection.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Don't set chan_timer for ATT fixed channel

According to Core spec (see Vol 3, Part A, 6.2.1), the channel timer
used to terminate the channel when the remote endpoint is unreponsive
to signaling requests. Since there is no signaling requests in LE ATT
fixed channel, there is no need we setup this timer.

As a side effect, LE connection attempts won't be aborted by the
channel timer anymore. Therefore, SOCK_NONBLOCK LE L2CAP sockets will
be ready (will receive POLLOUT event) when the LE connection is
established.

This patch modifies l2cap_chan_connect function so it doesn't set
the timer if the cid is L2CAP_CID_LE_DATA.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>