Bluetooth: ISO: Make iso_get_sock_listen generic

This makes iso_get_sock_listen more generic, to return matching socket
in the state provided as argument.

Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>