Return the inventory information from the device.

def get_inventory_text(self):
        """Return the inventory information from the device."""
        inventory_text = None
        if self.inventory_cmd:
            try:
                inventory_text = self.device.send(self.inventory_cmd, timeout=120)
                self.log('Inventory collected')
            except CommandError:
                self.log('Unable to collect inventory')
        else:
            self.log('No inventory command for {}'.format(self.platform))
        return inventory_text