mac80211: remove useless NULL checks

sdata can't be NULL, and key being NULL is really not possible
unless the code is modified.

The sdata check made a static analyze (klocwork) unhappy because
we would get pointer to local (sdata->local) and only then check
if sdata is non-NULL.

Signed-off-by: Eytan Lifshitz <eytan.lifshitz@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
[remove !key check as well]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/key.c

@@ -482,9 +482,6 @@ int ieee80211_key_link(struct ieee80211_key *key,
 	int idx, ret;
 	bool pairwise;
 
-	if (WARN_ON(!sdata || !key))
-		return -EINVAL;
-
 	pairwise = key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE;
 	idx = key->conf.keyidx;
 	key->local = sdata->local;