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:
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.