fault-inject: fix inverted interval/probability values in printk

interval displays the probability and vice versa.

Fixes: 6adc4a22

 ("fault-inject: add ratelimit option")
Acked-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>