FROMGIT: software node: Introduce device_add_software_node()

This helper will register a software node and then assign
it to device at the same time. The function will also make
sure that the device can't have more than one software node.

Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20210115094914.88401-2-heikki.krogerus@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit e68d0119
 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git

 usb-next)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Id39b4ec26476b5b07aa256e0c878e5cc5ed19ef5