mac80211: initialize SMPS field in HT capabilities

ibss and mesh modes copy the ht capabilites from the band without
overriding the SMPS state. Unfortunately the default value 0 for the
SMPS field means static SMPS instead of disabled.

This results in HT ibss and mesh setups using only single-stream rates,
even though SMPS is not supposed to be active.

Initialize SMPS to disabled for all bands on ieee80211_hw_register to
ensure that the value is sane where it is not overriden with the real
SMPS state.
Reported-by: Elektra Wagenrad <onelektra@gmx.net>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
[move VHT TODO comment to a better place]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/main.c

@@ -913,12 +913,17 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 		supp_ht = supp_ht || sband->ht_cap.ht_supported;
 		supp_vht = supp_vht || sband->vht_cap.vht_supported;
 
-		if (sband->ht_cap.ht_supported)
+		if (!sband->ht_cap.ht_supported)
+			continue;
+
+		/* TODO: consider VHT for RX chains, hopefully it's the same */
 		local->rx_chains =
 			max(ieee80211_mcs_to_chains(&sband->ht_cap.mcs),
 			    local->rx_chains);
 
-		/* TODO: consider VHT for RX chains, hopefully it's the same */
+		/* no need to mask, SM_PS_DISABLED has all bits set */
+		sband->ht_cap.cap |= WLAN_HT_CAP_SM_PS_DISABLED <<
+			             IEEE80211_HT_CAP_SM_PS_SHIFT;
 	}
 
 	/* if low-level driver supports AP, we also support VLAN */