mac80211: free netdev on dev_alloc_name() error

The change to remove free_netdev() from ieee80211_if_free()
erroneously didn't add the necessary free_netdev() for when
ieee80211_if_free() is called directly in one place, rather
than as the priv_destructor. Add the missing call.

Fixes: cf124db5 ("net: Fix inconsistent teardown and release of private netdev state.")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>