iwlwifi: clear dbg_fixed_rate during init

This prevent bad fixed_rate keeps crashing uCode in an endless loop.
Signed-off-by: NShanyu Zhao <shanyu.zhao@intel.com>
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>

drivers/net/wireless/iwlwifi/iwl-agn-rs.c

@@ -2873,6 +2873,8 @@ void iwl_rs_rate_init(struct iwl_priv *priv, struct ieee80211_sta *sta, u8 sta_i
 		lq_sta->last_txrate_idx += IWL_FIRST_OFDM_RATE;
 	lq_sta->is_agg = 0;
 
+	lq_sta->dbg_fixed_rate = 0;
+
 	rs_initialize_lq(priv, conf, sta, lq_sta);
 }