wifi: cfg80211: reject duplicate wiphy cipher suite entries

In the Linux kernel, the following vulnerability has been resolved: wifi: cfg80211: reject duplicate wiphy cipher suite entries Duplicate entries in wiphy->cipher_suites do not describe any additional capability, but cfg80211 currently accepts them and leaves individual consumers to deal with them. One such consumer is the WEXT compatibility code, which appends a WEP key length for each WEP cipher entry it sees. Repeated WEP entries can therefore overflow the fixed iw_range::encoding_size array returned by SIOCGIWRANGE. Reject duplicate cipher suite entries in wiphy_register() instead. This keeps the cipher suite invariant in one place and makes malformed wiphy descriptions fail early with -EINVAL, rather than relying on a single cfg80211 user to handle duplicates correctly.