nl80211: Work around mac80211 limitation on (re)auth when authenticated

nl80211: Work around mac80211 limitation on (re)auth when authenticated

mac80211 does not currently allow (re)authentication when we are already
authenticated. In order to work around this, force deauthentication if
nl80211 authentication command fails with EALREADY. Unfortunately, the
workaround code in driver_nl80211.c alone is not enough since the
following disconnection event would clear wpa_supplicant authentication
state. To handle this, add some code to restore authentication state
when using userspace SME.

This workaround will hopefully become unnecessary in some point should
mac80211 start accepting new authentication requests even when in
authenticated state.