when the second, third... probe is registered, its format is
not checked, this patch fixes it.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: NIngo Molnar <mingo@elte.hu>