[PATCH] kobject: quiet errors in kobject_add

People don't like released kernels yelling at them, no matter how real the
error might be.  So only report it if CONFIG_KOBJECT_DEBUG is enabled.

Sent on request of Andrew Morton.

(akpm: should bring this back post-2.6.17)

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>