Thanks to drivers making their id tables __devinit, we can't allow
userspace to bind or unbind drivers from devices manually through sysfs.
So we only allow this if CONFIG_HOTPLUG is enabled.

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>