Fix typo in cntl_msg_types

[wengzhe]

I think this should be a typo (cntl_msg_types vs ctnl_msg_types), but I'm not sure whether we can change the type name in uAPI headers (which seems to be not used anywhere).

I tried to search cntl_msg_types on https://bugzilla.kernel.org but got nothing. I've also tried to search this typo by search engine but only found one repo indicating this typo https://github.com/ti-mo/conntrack/blob/7ac9c2a61f2dc6d042b0d1bd53881ca84f09aa4e/enum.go#L17

So I came here to see how we should deal with this kind of typos.