iwlwifi: clear dbg_fixed_rate during init

This prevent bad fixed_rate keeps crashing uCode in an endless loop.

Signed-off-by: Shanyu Zhao <shanyu.zhao@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
index f450adc..ee12348 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
@@ -2873,6 +2873,8 @@
 		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);
 }