[PATCH] drivers/base/bus.c warning fixes

drivers/base/bus.c:166: warning: `driver_attr_unbind' defined but not used
drivers/base/bus.c:194: warning: `driver_attr_bind' defined but not used

Looks like these two attributes and supporting functions want to be
#ifdef HOTPLUG'd

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>