patches for if_iwi and wlan for WEP mode

[Mitsuru IWASAKI]

> I'd rather you file a PR first describing what you just did, then
> commit the fix and close the PR.

OK, I've just submitted a PR.  I'll follow the procedure you suggested.

http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/165819

Thanks