greybus: Documentation/sysfs: make 1-5 a 2x2 module

greybus: Documentation/sysfs: make 1-5 a 2x2 module

Make example module 1-5 a 2x2 module by adding a second, dummy
interface.

This is both an example of how a 2x2 module would be represented and
also suggests what a dummy interface may look like.

A 2x2 module has two child interface devices and a num_interfaces value
of two.

In this example, the secondary interface 1-5.6, is a dummy interface and
therefore lacks the normal identifying attributes (e.g. UniPro DDBL1 and
Ara ids). We may eventually add an interface_type attribute to
facilitate distinguishing various interface types (there may be more
than two).

In the following tree, the bundle attributes and child devices have been
left out:

greybus1/
├── 1-2
│   ├── 1-2.2
│   │   ├── 1-2.2.1
│   │   ├── 1-2.2.2
│   │   ├── ddbl1_manufacturer_id
│   │   ├── ddbl1_product_id
│   │   ├── interface_id
│   │   ├── product_id
│   │   ├── serial_number
│   │   ├── unique_id
│   │   └── vendor_id
│   ├── eject
│   ├── module_id
│   └── num_interfaces
├── 1-5
│   ├── 1-5.5
│   │   ├── 1-5.5.2
│   │   ├── ddbl1_manufacturer_id
│   │   ├── ddbl1_product_id
│   │   ├── interface_id
│   │   ├── product_id
│   │   ├── serial_number
│   │   ├── unique_id
│   │   └── vendor_id
│   ├── 1-5.6
│   │   └── interface_id
│   ├── eject
│   ├── module_id
│   └── num_interfaces
└── 1-svc

In this example there are two modules: 1-2 is a 1x2 module with one
interface, and 1-5 is a 2x2 module with two interfaces of which the
second (1-5.6) is a dummy interface.

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>