rtw88: add fast xmit support

With dynamic power save support, rtw88 is able to support fast tx
path, claim it to mac80211.
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtw88/main.c

@@ -1168,6 +1168,7 @@ int rtw_register_hw(struct rtw_dev *rtwdev, struct ieee80211_hw *hw)
 	ieee80211_hw_set(hw, REPORTS_TX_ACK_STATUS);
 	ieee80211_hw_set(hw, SUPPORTS_PS);
 	ieee80211_hw_set(hw, SUPPORTS_DYNAMIC_PS);
+	ieee80211_hw_set(hw, SUPPORT_FAST_XMIT);
 
 	hw->wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION) |
 				     BIT(NL80211_IFTYPE_AP) |