software node: Deduplicate code in fwnode_create_software_node()

Deduplicate conditional and assignment in fwnode_create_software_node(),
i.e. parent is checked in two out of three cases and parent software node
is assigned by to_swnode() call.

Reviewed-by: Daniel Scally <djrscally@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210329151207.36619-3-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>