kobject: align stacktrace levels to logging message

Without an explicit level the stacktraces are printed at a default
level.
If this level does not match the one from the logging level it may
happen that the stacktrace is shown without the message or vice versa.

Both these cases are confusing, so make sure the user always sees both,
the message and the stacktrace.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20230311-kobject-warning-v1-2-1ebba4f71fb5@weissschuh.net


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>