Bluetooth: Search global l2cap channels by src/dst addresses

The cid or psm and the source address might not be enough to uniquely
identify a global channel, especially when the source address is our
own.

For instance, when trying to communicate with two LE devices in master
mode, data received from the both devices is sent to the same socket.

Fix this by taking the destination address into account when choosing
the socket.

Signed-off-by: Ido Yariv <ido@wizery.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Tested-by: João Paulo Rechi Vita <jprvita@openbossa.org>
Signed-off-by: Gustavo Padovan <gustavo@padovan.org>