ath10k: ensure rx-frag ignores rssi

It seems ath10k firmware gives us no way to know
the rssi for rx-fragments.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/htt_rx.c

@@ -1326,6 +1326,7 @@ static void ath10k_htt_rx_frag_handler(struct ath10k_htt *htt,
 	}
 
 	/* FIXME: implement signal strength */
+	rx_status->flag |= RX_FLAG_NO_SIGNAL_VAL;
 
 	hdr = (struct ieee80211_hdr *)msdu_head->data;
 	rxd = (void *)msdu_head->data - sizeof(*rxd);