Remove the assumption that driver_register() returns the number of devices
bound to the driver.  In fact, it returns zero for success or a negative
error value.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Acked-by: Jeff Garzik <jgarzik@pobox.com>
Acked-by: Marc Zyngier <maz@misterjones.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>