greybus: Documentation/sysfs: add entry for control device

Add an entry for the recently added interface control device.

Also move the bundle-device entry below the control-device entries.

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