driver core: don't fail attaching the device if it cannot be bound

Don't fail bus_attach_device() if the device cannot be bound.

If dev->driver has been specified, reset it to NULL if device_bind_driver()
failed and add the device as an unbound device.  As a result,
bus_attach_device() now cannot fail, and we can remove some checking from
device_add().

Also remove an unneeded check in bus_rescan_devices_helper().

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 616b4bb..18dba8e 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -232,7 +232,7 @@
  *
  *	Returns 1 if the device was bound to a driver;
  *	0 if no matching device was found or multithreaded probing is done;
- *	error code otherwise.
+ *	-ENODEV if the device is not registered.
  *
  *	When called for a USB interface, @dev->parent->sem must be held.
  */
@@ -246,6 +246,10 @@
 		ret = device_bind_driver(dev);
 		if (ret == 0)
 			ret = 1;
+		else {
+			dev->driver = NULL;
+			ret = 0;
+		}
 	} else {
 		if (dev->bus->multithread_probe)
 			probe_task = kthread_run(device_probe_drivers, dev,