iwlwifi: mvm: add lq_cmd/tx_resp reduced_tpc field

The fw recently added an option to set tx power reduction
per station (in the lq_cmd command), and get the tx power
reduction used (in the tx_resp struct).

Use them and propogate this value up to mac80211's tx
response (in order to use it later in the rate-scaling
algorithm).

Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/iwlwifi/mvm/fw-api-tx.h

@@ -482,7 +482,8 @@ struct iwl_mvm_tx_resp {
 	u8 pa_integ_res_b[3];
 	u8 pa_integ_res_c[3];
 	__le16 measurement_req_id;
-	__le16 reserved;
+	u8 reduced_tpc;
+	u8 reserved;
 
 	__le32 tfd_info;
 	__le16 seq_ctl;