mac80211: check ERP info IE length in parser

It's always just one byte, so check for that and
remove the length field from the parser struct.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index f76c58f..157d951 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -3038,7 +3038,7 @@
 		changed |= BSS_CHANGED_DTIM_PERIOD;
 	}
 
-	if (elems.erp_info && elems.erp_info_len >= 1) {
+	if (elems.erp_info) {
 		erp_valid = true;
 		erp_value = elems.erp_info[0];
 	} else {