iwlwifi: mvm: rs: fix a potential NULL deref

Found by klocwork analysis.
mvm could be NULL which may cause a NULL dereference
in a theoretical call flow

rs_fill_lq_cmd(mvm = NULL, ...)
rs_build_rates_table
rs_fill_rates_for_column
ucode_rate_from_rs_rate
IWL_ERR(mvm,...)

No real reason for passing NULL to rs_fill_lq_cmd so fix that.
Reported-by: Eytan Lifshitz <eytan.lifshitz@intel.com>
Signed-off-by: Eyal Shapira <eyal@wizery.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/iwlwifi/mvm/rs.c

@@ -2121,7 +2121,7 @@ static void rs_initialize_lq(struct iwl_mvm *mvm,
 		tbl->column = RS_COLUMN_LEGACY_ANT_B;
 
 	rs_set_expected_tpt_table(lq_sta, tbl);
-	rs_fill_lq_cmd(NULL, NULL, lq_sta, rate);
+	rs_fill_lq_cmd(mvm, sta, lq_sta, rate);
 	/* TODO restore station should remember the lq cmd */
 	iwl_mvm_send_lq_cmd(mvm, &lq_sta->lq, init);
 }
@@ -2448,8 +2448,7 @@ static void rs_build_rates_table(struct iwl_mvm *mvm,
 
 	memcpy(&rate, initial_rate, sizeof(rate));
 
-	if (mvm)
-		valid_tx_ant = iwl_fw_valid_tx_ant(mvm->fw);
+	valid_tx_ant = iwl_fw_valid_tx_ant(mvm->fw);
 
 	if (is_siso(&rate)) {
 		num_rates = RS_INITIAL_SISO_NUM_RATES;
@@ -2623,7 +2622,7 @@ static void rs_program_fix_rate(struct iwl_mvm *mvm,
 		struct rs_rate rate;
 		rs_rate_from_ucode_rate(lq_sta->dbg_fixed_rate,
 					lq_sta->band, &rate);
-		rs_fill_lq_cmd(NULL, NULL, lq_sta, &rate);
+		rs_fill_lq_cmd(mvm, NULL, lq_sta, &rate);
 		iwl_mvm_send_lq_cmd(lq_sta->drv, &lq_sta->lq, false);
 	}
 }