cfg80211: Allow use_mfp to be specified with the connect command

The NL80211_ATTR_USE_MFP attribute was originally added for
NL80211_CMD_ASSOCIATE, but it is actually as useful (if not even more
useful) with NL80211_CMD_CONNECT, so process that attribute with the
connect command, too.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>