ath11k: enable IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS for WCN6855

Currently mac80211 will send 3 scan request for each scan of WCN6855,
they are 2.4 GHz/5 GHz/6 GHz band scan. Firmware of WCN6855 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 WCN6855 since
it supports 2.4 GHz/5 GHz/6 GHz and it is single pdev which means
all the 2.4 GHz/5 GHz/6 GHz exist in the same wiphy/ieee80211_hw.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-01720.1-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1
Tested-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20211129101309.2931-1-quic_wgong@quicinc.com

drivers/net/wireless/ath/ath11k/mac.c

@@ -8119,6 +8119,9 @@ static int __ath11k_mac_register(struct ath11k *ar)
 
 	ar->hw->wiphy->interface_modes = ab->hw_params.interface_modes;
 
+	if (ab->hw_params.single_pdev_only && ar->supports_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);