Impact: fix bug

the third param in module_param(,,) is perm instead of default value.
we still need to assign default at first.  Also, the default is now
zero not one, so fix the parameter text to reflect that.
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NKashyap Desai <kadesai@lsi.com>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>