drivers/pci/pci-driver.c: warn on driver probe return value greater than zero

drivers/pci/pci-driver.c: warn on driver probe return value greater than zero

Ages ago, drivers could return values greater than zero from their probe
function and this would be regarded as success.  Commit f3ec4f87d607f40497
"PCI: change device runtime PM settings for probe and remove" slightly
altered this in 2010, and commit 967577b062417b4e4b8e27b ("PCI/PM: Keep
runtime PM enabled for unbound PCI devices") in late 2012 altered it more
signficantly, setting pci_dev->driver to NULL if the driver's probe
function returned a value greater than zero, which would for example
prevent the driver's remove function from being called on rmmod.

Neither of those changes would necessarily make the driver fail in an
obvious way though, and so at least a couple drivers (cciss, hpsa) fell
into this hole since they were returning 1, and this situation went
unnoticed for quite some time.

If a driver's probe function returns a value greater than zero, issue a
warning, but otherwise treat this as success.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>