Bluetooth: Add le_auto_conn file on debugfs

Bluetooth: Add le_auto_conn file on debugfs

This patch adds to debugfs the le_auto_conn file. This file will be
used to test LE auto connection infrastructure.

This file accept writes in the following format:
  "add <address> <address_type> [auto_connect]"
  "del <address> <address_type>"
  "clr"

The <address type> values are:
  * 0 for public address
  * 1 for random address

The [auto_connect] values are (for more details see struct hci_
conn_params):
  * 0 for disabled (default)
  * 1 for always
  * 2 for link loss

So for instance, if you want the kernel autonomously establishes
connections with device AA:BB:CC:DD:EE:FF (public address) every
time the device enters in connectable mode (starts advertising),
you should run the command:
$ echo "add AA:BB:CC:DD:EE:FF 0 1" > /sys/kernel/debug/bluetooth/hci0/le_auto_conn

To delete the connection parameters for that device, run the command:
$ echo "del AA:BB:CC:DD:EE:FF 0" > /sys/kernel/debug/bluetooth/hci0/le_auto_conn

To clear the connection parameters list, run the command:
$ echo "clr" > /sys/kernel/debug/bluetooth/hci0/le_auto_conn

Finally. to get the list of connection parameters configured in kernel,
read the le_auto_conn file:
$ cat /sys/kernel/debug/bluetooth/hci0/le_auto_conn

This file is created only if LE is enabled.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>