staging: comedi: support auto_attach() for PCI and USB

Allow `comedi_pci_auto_config()` and `comedi_usb_auto_config()` to use
the new `auto_attach()` hook in the low-level driver's `struct
comedi_driver` if it is set and the `attach_pci()` or `attach_usb()`
hook (for PCI or USB respectively) is `NULL`.

Eventually, the `auto_attach()` hook will be the only way of
auto-configuring hardware devices as comedi devices and the bus-type
specific `attach_pci()` and `attach_usb()` hooks will be removed.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers.c

@@ -1023,6 +1023,8 @@ int comedi_pci_auto_config(struct pci_dev *pcidev, struct comedi_driver *driver)
 
 	if (driver->attach_pci)
 		return comedi_new_pci_auto_config(pcidev, driver);
+	else if (driver->auto_attach)
+		return comedi_auto_config(&pcidev->dev, driver, 0);
 	else
 		return comedi_old_pci_auto_config(pcidev, driver);
 }
@@ -1093,6 +1095,8 @@ int comedi_usb_auto_config(struct usb_interface *intf,
 	BUG_ON(intf == NULL);
 	if (driver->attach_usb)
 		return comedi_new_usb_auto_config(intf, driver);
+	else if (driver->auto_attach)
+		return comedi_auto_config(&intf->dev, driver, 0);
 	else
 		return comedi_old_usb_auto_config(intf, driver);
 }