mac80211: don't check if key is NULL in ieee80211_key_link()

We already assume that key is not NULL and dereference it in a few
other places before we check whether it is NULL, so the check is
unnecessary.  Remove it.

Fixes: 96fc6efb ("mac80211: IEEE 802.11 Extended Key ID support")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/20190830112451.21655-8-luca@coelho.fi


Signed-off-by: Johannes Berg <johannes.berg@intel.com>