wifi: ath12k: enable IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS for WCN7850

Currently mac80211 will send 3 scan request for each scan of WCN7850, they
are 2.4 GHz/5 GHz/6 GHz band scan. Firmware of WCN7850 will cache the RNR
IE(Reduced Neighbor Report element) which exist in the beacon of 2.4 GHz/5
GHz of the AP which is co-located with 6 GHz, and then use the cache to
scan in 6 GHz band scan if the 6 GHz scan is in the same scan with the 2.4
GHz/5 GHz band, this will helpful to search more AP of 6 GHz. Also it will
decrease the time cost of scan because firmware will use dual-band scan
for the 2.4 GHz/5 GHz, it means the 2.4 GHz and 5 GHz scans are doing
simultaneously.

Set the flag IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS for WCN7850 since it
supports 2.4 GHz/5 GHz/6 GHz in a single wiphy/ieee80211_hw.

This does not impact QCN9274, because it is not single_phy, so does not
have 2.4 GHz/5 GHz/6 GHz in the same wiphy, then it does not match the
condition and then IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS will not set for
QCN9274.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0-03427-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.15378.4
Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230913105507.17675-1-quic_wgong@quicinc.com

drivers/net/wireless/ath/ath12k/mac.c

@@ -7311,6 +7311,11 @@ static int __ath12k_mac_register(struct ath12k *ar)
 
 	ar->hw->wiphy->interface_modes = ab->hw_params->interface_modes;
 
+	if (ar->hw->wiphy->bands[NL80211_BAND_2GHZ] &&
+	    ar->hw->wiphy->bands[NL80211_BAND_5GHZ] &&
+	    ar->hw->wiphy->bands[NL80211_BAND_6GHZ])
+		ieee80211_hw_set(ar->hw, SINGLE_SCAN_ON_ALL_BANDS);
+
 	ieee80211_hw_set(ar->hw, SIGNAL_DBM);
 	ieee80211_hw_set(ar->hw, SUPPORTS_PS);
 	ieee80211_hw_set(ar->hw, SUPPORTS_DYNAMIC_PS);