cfg80211: drop duplicated documentation of field "perm_addr"

The field "perm_addr" was already documented above the definition of
struct wiphy. Comments were almost identical.
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200221115604.594035-5-Jerome.Pouiller@silabs.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -4598,7 +4598,6 @@ struct wiphy_iftype_akm_suites {
 struct wiphy {
 	/* assign these fields before you register the wiphy */
 
-	/* permanent MAC address(es) */
 	u8 perm_addr[ETH_ALEN];
 	u8 addr_mask[ETH_ALEN];